England XI 414 for 6 dec (Cook 126, Root 117, Stokes 66, Hales 56, Maharaj 4-129) beat South Africa A 136 (Cook 53*, Finn 4-34) and 187 (de Kock 53, Moeen 6-77) by an innings and 91 runs

Moeen Ali was the latest member of the England side to gain form ahead of the Boxing Day Test in the tour match at Pietermartizburg.

Moeen, finding sharp turn and bowling with increasing control, claimed the sixth five-wicket haul of his first-class career to help England seal an innings-and-91-run victory against South Africa A. He finished with 6 for 77.

Moeen's spell completed an almost perfect match for England. As well as seeing Steven Finn prove his form and fitness, the match also included Joe Root and Alastair Cook scoring centuries and Alex Hales and Ben Stokes half-centuries. Every one of the top six has now scored a half-century in one of the two warm-up games and all the bowlers, with the exception of the protected James Anderson, have proved their readiness.

While much of the focus has been on the two side's seam attacks, spin could also play a key role in the series. Graeme Swann, who claimed 21 wickets in the 2009-10 series with his offspin, was the highest wicket-taker on either side the last time England toured here. He also took nine wickets in the Durban Test.

The Durban area is currently suffering from drought and, with temperatures touching 40 degrees at times, the pitch could well prove unusually dry. Dolphins, the franchise team that play in Durban, have recently fielded two spinners in their XI.

So to see Moeen gain rhythm ahead of the series will have been particularly pleasing for England. After bowling Reeza Hendricks through the gate on the previous evening, he defeated Quinton de Kock with one that straightened as the batsman tried to play the ball through the leg side. Rilee Rossouw missed a sweep, Chris Morris an arm ball and Keshav Maharaj, after some merry slogging, was bowled round his legs.

While there were, in the early overs of his spell, three long-hops that were cut to the boundary, Moeen's control improved significantly as his rhythm and confidence grew. With some balls turning sharply and others skidding on through natural variation, he proved a tricky proposition, though his figures were damaged by some late slogging from the tail.

After what he termed a "tough" tour of the UAE, it was important for Moeen to gain some confidence ahead of the this series. He claimed only nine wickets across the three Tests, with each of them costing on average 48.66.

"I felt the Pakistanis played me really well," Moeen said. "They were the best I've ever bowled at. They never once let me settle and knocked me around. It was tough. But I felt like I learned so much from the UAE than I had done in the last couple of years before that.

"If it spins I'll try and keep it as simple as I can and if it's not spinning I'll try and hold up an end. I don't do that very well but it's something I've been working on since I've been here and hopefully I can do that.

"I've worked on my action a little bit to make it consistent. In the last couple of years I've changed my action quite a bit and I was always searching, but I feel like I've found something that helps me now. I bowled a lot more lately as well than I have done in the past.

"Naturally I try and bowl through the gate and look for those balls but on these wickets you probably won't get that as much so you need to just bowl tight and bowl to my field as much as I can. It's not easy when guys come at you but it gives you a chance of getting wickets."

The only concern will have been two chances spurned in the field. Jonny Bairstow missed a relatively straightforward stumping after de Kock had been drawn down the pitch and beaten by turn by a beauty from Moeen, while Alex Hales missed what, by these standards, has to be considered an easy catch at deep midwicket after Keshav Maharaj miscued an attempted slog. He made amends a few minutes later by clinging on to Dane Paterson in similar circumstances.

It is the Bairstow error that will concern England most. While his keeping standing back has improved - he was said to have enjoyed his best training session to date earlier this week - his work standing up to the stumps does not yet warrant the same confidence. And as England found in 2012, if you give a life against South Africa, you are liable to pay a heavy price. Hashim Amla was dropped on 2 by Matt Prior at Lord's, where he went on to make a century, and on 40 in the slips at The Oval, where he made a triple century. South Africa won both Tests.

Still, this has been a close to perfect warm-up match for England. Their record in opening Tests of away series is far from good - since beating South Africa, at Port Elizabeth, in 2004 they have only won one, against Bangladesh in 2010 - but they may feel they are well prepared for the start of this series as they have been for a long time.

George Dobell is a senior correspondent at ESPNcricinfo