Last season: Winners
Director of Cricket: Adam Carty
Coach: Charlotte Edwards
Captain:Georgia Adams

The Vipers stormed to the title in the inaugural season of the Rachael Heyhoe Flint Trophy, winning all six group games and defending 231 in the final against Northern Diamonds at Edgbaston. They had the competition's leading run-scorer and wicket-taker in Georgia Adams and Charlotte Taylor respectively, and were the dominant force throughout the season.

The challenge this year is to back those performances up when England players are available for a greater proportion of the season. The Vipers will be boosted by the returns of Danni Wyatt and Georgia Elwiss but it will be a major test for their less experienced players to come up against internationals on a more regular basis.

Both of those returning England players bring intrigue. Wyatt, a T20 firestarter by trade, has never quite cracked ODI cricket and has struggled for international runs since the start of 2020. She was given Lisa Keightley's backing despite a lean series in New Zealand earlier this year, but comes into this season under scrutiny; with Adams anchoring the innings alongside her, she should have licence to play her shots. Elwiss, meanwhile, has not made it onto the field in an England shirt since July 2019, and missed the whole of last summer with a back injury. She will be desperate to provide a reminder of her all-round worth.

Key player: The biggest test of the season will come if Adams' domestic form is rewarded with an England call-up. Her captaincy last year - in combination with Charlotte Edwards' leadership as head coach - galvanised the squad and her consistency with the bat has not gone unnoticed. She might well have been considered for England's tour to New Zealand over the winter but for shoulder surgery, and if she is named in the squads for the India series - likely to be announced in within the next two weeks - then the Vipers will feel her absence keenly.

One to watch: Lauren Bell is a tall seamer who bowls hooping inswingers and finds sharp bounce from a good length. She took seven wickets in four appearances last season, spending most of the summer in England's training group in the Derby bubble, but should have the opportunity to lead the attack alongside Tara Norris throughout this year. Still only 20, she is one of England's best young seam-bowling prospects, alongside Central Sparks tearaway Issy Wong.

Last season: Runners-up
Director of Cricket: James Carr
Coach: Danielle Hazell
Captain: Hollie Armitage

Beaten by Southern Vipers in the final, the Diamonds are looking to go one better this year. Having reached 74 for 1 in the decider, the Diamonds' collapse to 96 for 6 hurt them as they were bowled out for 193 inside 43 overs at the hands of Charlotte Taylor's stunning six-wicket haul.

If they can take advantage of having the likes of England stars Katherine Brunt and Nat Sciver in their ranks for the early part of the season, the Diamonds should be able to inflict some damage on their opponents. From there, it will be down to those that are left to kick on once international duty calls.

Among them, Jenny Gunn provides vast all-round experience, Beth Langston was their leading wicket-taker last year with 12 at 19.41 and Dutch player Sterre Kalis offers big run-scoring potential. After three ducks in a row last season, Kalis struck three consecutive fifties to lead the team ahead of Hollie Armitage and Gunn. If Kalis can press on from the outset, it will stand her side in good stead.

Key player: Lauren Winfield-Hill is on a mission to make an England opening berth her own again and she started well with an unbeaten 140 for England Women A against England Women in a pre-season warm-up earlier this month. Time in the England squad bubble restricted her to just three matches in the Rachael Heyhoe Flint Trophy last season, with a highest score of 72 in her overall tally of 93 runs. Having finally settled into a treatment regimen in recent months for Crohn's disease, she is feeling and performing better physically, which can only mean good things for the Diamonds, if not England.

One to watch: Bess Heath, the 19-year-old wicketkeeper-batter, signalled her early form with a quick-fire 30 off 20 balls in a recent pre-season friendly against England Academy, including four fours and a six. Home-schooled throughout her secondary education, often through hands-on outdoor learning, Heath's love of cricket was forged through playing the game with her three older brothers. With eight catches, she had the most dismissals of any keeper in the competition last year.

Last season 2nd, South Group
Director of cricket Lisa Pagett
Coach Mark O'Leary
Captain Sophie Luff

Western Storm spent the Kia Super League years vying with Southern Vipers to be considered the dominant force, and that rivalry extended into the inaugural RHF Trophy. Storm won four out of their six matches in the group, but twice went down to the Vipers, who pipped them to top spot and went on to lift the title after an unbeaten campaign.

Although the squad has changed a fair bit since the KSL days, and highly rated former head coach Trevor Griffin is now at Sunrisers, Storm retain an air of white-ball knowhow: margins of victory by 86 runs, 47 runs, seven wickets and six wickets in their other group games hint at how strong they were. In captain Sophie Luff they had the tournament's third-leading run-scorer, while few sides could match the all-round depth provided by Georgia Hennessy (209 runs, 11 wickets), Fi Morris (115 runs, 11 wickets) and Alex Griffths (141 runs, three wickets).

Experienced offspinner Claire Nicholas is on maternity leave, but with their three England players available for the opening half of the tournament - captain Heather Knight taking her place in the ranks and Anya Shrubsole and Katie George primed for action after injury-disrupted winters - Storm are once again likely to be among the leading contenders.

Key player: Still waiting for a chance with England, Luff is a giant of the domestic scene in the West Country. Storm's No. 3 has shone in the pre-contract era, twice a KSL winner and mainstay with Somerset. At 27 and playing as well as ever, there is still time to make an unanswerable case for inclusion at the next level.

One to watch: Nat Wraith, 19, is a "wicketkeeper who gets on with it with the bat", according to Knight. Bristol born and currently studying at Cardiff University, she cites South Africa's Quinton de Kock as her favourite player. Wraith played all six games in last year's RHF Trophy, tallying 111 runs at 22.20 - including 68 off 75 against the Vipers - and winning an ECB domestic deal.

Last season: 2nd, North Group
Director of cricket Laura MacLeod
Coach Lloyd Tennant
Captain Eve Jones

The Sparks finished runners-up behind RHF finalists Northern Diamonds in 2020, and were the only team to beat the Headingley-based outfit during the group stage. Opening batter and captain Eve Jones led from the front, although they were perhaps over reliant on runs from the top order - only Jones, Marie Kelly and Gwenan Davies managed to pass 100 for the campaign.

To kick on, the Sparks will hope for greater returns from a clutch of young batters including Poppy Davies, Chloe Hill - the pair who made sure of victory over the Diamonds with an unbroken 46-run fifth-wicket stand at Headingley - and Milly Home. Allrounder Clare Boycott was fourth in the run-scoring with a mere 53, and she was also joint-leading wicket-taker with eight, alongside legspinner Anisha Patel. On their day Liz Russell, who claimed 4 for 28 against the Diamonds, and Issy Wong, wrecker of the Thunder top order at Edgbaston, could be match-winners with the ball, too.

The availability of their England pair, aggressive wicketkeeper-batter Amy Jones and legspinner Sarah Glenn, who is also looking to burnish her allrounder credentials, should give them even greater cutting edge. Ria Fackrell, a top-order batter and offspinner who arrived over the winter from Lightning, also adds to their options.

Key player: With 334 runs at 66.80, including a century and two fifties, to finish fourth on the competition run-scorers' list, Eve Jones was in fine form last season. If she and namesake Amy (no relation) get going against the new ball, it could be a case of keeping up with the Joneses for opposing teams this year.

One to watch: Look no further than Issy Wong. The 19-year-old joined England's tour to New Zealand over the winter in a development capacity, and as a pace bowler has ambitions to hit the 80mph mark - never previously achieved in women's cricket. With her penchant for a funky haircut and ability to solve a Rubik's cube in circa 30 seconds, there's plenty to like.

Last season: 3rd, South Group
Director of Cricket: Richard Bedbrook
Coach: Johann Myburgh
Captain:Tash Farrant

The Stars' first season in the regional domestic structure was a mixed bag: they were beaten home and away by the top two in the South Group, but cruised to wins against bottom club Sunrisers to finish third. They used a competition-high 18 players, and the result was that there were few standout performers: Tash Farrant, the captain, won an England recall thanks to her nine wickets in six games, but no batter managed to score 150 runs across the season.

As a result, improvements with the bat will be crucial to their chances this summer. They have two teenagers with great potential in Chloe Brewer and Alice Capsey, while Aylish Cranstone - who will have made significant strides forward over the winter as a contracted player and Susie Rowe - back in the game after several years focusing on her hockey career - bring some experience. Sophia Dunkley, who is almost certain to receive more England opportunities this season, will be vital in the early stages.

Dunkley is one of a number of players who could be lost to England duty, and international call-ups could well have a significant impact on the Stars' season. Farrant, Freya Davies, Alice Davidson-Richards and Bryony Smith may all miss fixtures at some stage, leaving a big hole in the bowling attack. As a result, it is vital that they hit the ground running while all of them are available and hope their uncapped players can cover the gaps later in the summer.

Key player: Farrant's performances and subsequent England recall last year were crucial in demonstrating the clear new path from domestic success to international cricket, but also set the tone for the rest of the Stars' attack with the new ball. Her ability to chip in with some lower-middle-order runs and her captaincy will be vitally important, too - though if she is picked for England's series against India, she will be a huge loss.

One to watch: "If you want to know who's going to be opening the batting for England in five years' time, have a watch of the London Cup live stream right now," the journalist Raf Nicholson tweeted last summer. "Her name is Alice Capsey." Still only 16, Capsey is particularly strong hitting down the ground and through midwicket, as she demonstrated in a nerveless 73 not out off 75 balls in a successful chase against Sunrisers last summer. Having batting at No. 4 last season, she may shuffle further up this year.

Last season: 3rd, North Group
Director of Cricket: David Thorley
Coach: Paul Shaw
Captain:Alex Hartley

Thunder got the better of Lightning twice in as many meetings last year, although that proved to be of more meteorological than RHFT significance, as both sides finished off the pace in 3rd and 4th place respectively in the North Group.

If Thunder are to improve on that showing in 2021, then you can expect their gun spinner Sophie Ecclestone to be in the thick of the action. Still only 22, Ecclestone has risen to the top of the ICC's T20I rankings, having married impact and economy to devastating effect, and in what is still a young squad, her experience will be invaluable.

Regardless of how many games Ecclestone is available for, the Thunder squad won't be lacking spin options. The skipper, Alex Hartley, is another left-arm purveyor, as is Hannah Jones, who played all six of their RHFT matches last season and was awarded a full-time professional contract in the winter. And then there's Liberty Heap, a 17-year-old offie whose 3 for 34 was instrumental in the second of their wins over Lightning.

But the squad's success is likely to be defined by their other departments - notably the batting, which never really fired in 2020, with just three half-centuries, two of which came in their opening fixture as they posted 200 for the only time in the competition. Much will be expected of Emma Lamb, earmarked to bat at No.3, and Ellie Threlkeld, the wicketkeeper and No.4, as well as powerful Laura Marshall at the top of the order.

Key player: Kate Cross has been there or thereabouts in the England set-up for years now, but with Freya Davies now edging ahead of her in the pecking order, she may well be on hand to lead Thunder's seam attack through their campaign. If the pitches at the first-class venues turn out to be true, spin alone may not cut it.

One to watch: Given the whippersnappers in her midst, Natalie Brown is a relative old sweat at the age of 30. But she was the team's most consistent source of runs throughout the 2020 campaign, with 189 at 31.50. And what's more, she passed 25 in five of her six innings, but made a top score of 52, which implies there's more to come if she can apply herself with similar discipline this time around.

Last season: 4th, North Group
Director of Cricket: Ian Read
Coach: Rob Taylor
Captain: Kathryn Bryce

A tough campaign in last year's RHFT, marked by the loss of a glut of tight contests, was enlivened only by Lightning's twin victories over their Midlands rivals, Central Sparks, as they finished rock-bottom of the North Group. However, theirs is a squad with sufficient pedigree to make a better fist of things this year, not least thanks to the Sister Act on which their 2020 campaign was pinned.

Captain Kathryn Bryce was the tournament's second-highest wicket-taker with 14 scalps at 15.42, and chipped in with 141 runs at 28.20, while her younger sister and fellow Scotland international, Sarah, bossed their runs-charts with 395 at 79.00, second only to Southern Vipers' trophy-winning Georgia Adams.

And, assuming Bryce Minor maintains those levels, then the prospect of her teaming up with the returning England star, Tammy Beaumont, at the top of the order is mouthwatering. Kirstie Gordon, another Scot within the Lightning squad, albeit one who has long since pledged her allegiance to the Sassanachs, claimed just three wickets with her left-arm spin but was the squad's most economical performer.

Key player: Beaumont was available for just two Trophy fixtures last season due to the concurrent West Indies series, but she proved her eye is still in on the recent tour of New Zealand, averaging 231 in the ODIs with three consecutive half-centuries, before a further matchwinning 63 in the second T20I.

One to watch: The South Africa-born Michaela Kirk, 21, has hopes of using her dual-passport to one day play for England, but for the time being she arrives with a big reputation and a big opportunity to seize the limelight, having also been signed as one of Trent Rockets' overseas players for the Hundred. A hard-hitting batter in the mould of her mentor Mignon du Preez, she's been playing top-level domestic cricket since making her debut for Northerns as an offspinning 13-year-old in 2012.

Last season: 4th, South Group
Director of Cricket: Danni Warren
Coach: Trevor Griffin
Captain: Amara Carr

A young Sunrisers side - they range in age from 17 to 29 - went winless throughout the 2020 season but Danni Warren, their director of cricket, believes they will have grown from experience and exposure in the competition as well as six months training in a fully professional set-up, which includes Trevor Griffin, coach of reigning WBBL champions Sydney Thunder and a two-time KSL-winning coach with Western Storm.

Up-and-coming England spinner Mady Villiers and Fran Wilson, with 64 international appearances to her name, add depth alongside the likes of full-time contract holders Naomi Dattani, Cordelia Griffith and captain Amara Carr who are all former England Women's Academy members.

Right-arm seamer Sonali Patel, who has just turned 18, was the team's leading wicket-taker last season with seven, including 4 for 52 against South East Stars, while fellow right-arm seamer 20-year-old Katie Wolfe also took seven wickets, which bodes well for the future.

Key player: Jo Gardner, Sunrisers' leading run-scorer last year with 193 at 32.16, is among five women in the team who are expected to take the next step in their careers as full-time professionals. Gardner also claimed seven wickets with her off-breaks and is no slouch in the field. A keen golfer, Gardner has also secured a spot with Oval Invincibles for the Hundred.

One to watch: Now just 17, Grace Scrivens was second on Sunrisers' run-scoring charts last season with 137 at 22.83 and a highest score of 72. She also claimed three wickets with her off-spin and will undoubtedly have benefited from her experience playing all six matches of Sunrisers' campaign. This season, Scrivens scored 191 runs in six matches, including an unbeaten 94 off 62 balls against Surrey, as her Kent side went undefeated to win the Women's County T20 South East Group.