Not so long ago, in 1994-95, the balance of power between England and Australia - in one-day cricket at least - was such that Australia decided to add an A side to a tournament between the two nations and Zimbabwe, just to ensure a bit of competition. And, sure enough, the final of that Benson & Hedges World Series was played between Australia and Australia A after England managed to lose crucial matches to both Zimbabwe and Australia A.

So let nobody take the result of the Royal London Series lightly. Australia are the current World Cup holders and this was their best-available side. Their strength in depth is always enviable and, even in this series, they showed they had another fast bowler, in Billy Stanlake, who could enjoy a long career at this level. To have beaten them 5-0 - the first time England have managed such a feat - is worthy of respect. The fact that it follows a 4-1 victory in Australia, and that England have won 10 of the last 11 ODIs between the nations (and 12 from 14), underlines the new balance of power. There's nothing wrong in savouring this success.

There were several encouraging features of this success from an England perspective. There was the fact that four different batsmen - Jason Roy, Jonny Bairstow, Alex Hales and Jos Buttler - made at least one century during the series; there was the fact the top four wicket-takers - Adil Rashid, Moeen Ali, Liam Plunkett and David Willey - were England players; and that, having set a world-record score batting first in Nottingham they achieved the second-highest chase in their ODI history in Durham a couple of days later.

The batting line-up stretches over the horizon and the bowling, even without Chris Woakes (their top-ranked ODI bowler) and Ben Stokes fared better than might have been expected. England know their best 12 or 13 - it seems unlikely that, barring injury, anyone from the outside can force themselves in now - and they are rated the No. 1 ODI team by the ICC. Perhaps not since 1992 have they been better placed ahead of a World Cup year.

The manner of some of these victories - hard-fought and scrappy - and the fact they lost to Scotland barely two weeks ago, should stop England becoming too giddy. They required Willey, batting at No. 8, to see them to victory at The Oval and Jake Ball, surviving a maiden over at No. 11, to help them over the line in Manchester. There were moments, not least as Australia passed 300 in Cardiff, that the limitations of England's attack were apparent and times, such as when England subsided to 114 for 8 in Manchester or 163 for 6 at The Oval, when we were reminded they still have the odd batting collapse in them. One of those at the wrong moment can quickly derail a World Cup campaign.

And that is a nagging worry. For with so much invested in this pursuit of the 2019 World Cup - and English cricket has been building to it for more than three years now - there is an apparently unavoidable fragility to their plans that is bound to leave them mercy to an element of chance. There is also the concern that, with so much expected and required of this England side, their fearlessness could fade away when the spotlight is at its brightest.

It would be unfair to suggest they have simply gone all-in on red - they are far better than chancers - but there is discomfort in knowing that such a huge part of the strategy for England cricket over the last few years could be reliant on the toss of a coin or the foibles of the English weather.

Still, it's better to be pace-setters than no-hopers, as England were going into the 2015 World Cup. And it says something for the competition in the side that even Joe Root's place is now in question and, were it not for the fear of destabilising the team, Eoin Morgan's might be, too. Stokes will certainly return to the side when fit - Hales remains the most vulnerable - while Woakes was, perhaps, the more-missed of the two against Australia.

Root remains as the insurance policy should England find themselves playing a game in bowler-friendly conditions and, while Buttler looks every inch a captain in waiting, removing Morgan now would be to repeat the mistakes of many previous campaigns: a bit of stability doesn't do any harm. Besides, Morgan's statistics from the recent series - when he struck the quickest half-century in England's ODI history - aren't so bad: a batting average of 37.75 and a strike-rate of 126.89; higher than everyone involved except Bairstow.

No doubt Australia will be stronger by the time the World Cup starts. At least some of their faster bowlers should have returned; surely Steve Smith and David Warner, too. But Morgan made an interesting point after the match in Manchester. Reflecting on England's experiences going into the 2015 World Cup, he recalled "a generation of England players that had never won a game in Australia". While his memory was slightly faulty - England had actually lost seven of their previous eight ODIs against Australia in Australia before the group encounter (another defeat) in Melbourne - the point still holds: "there was a big mountain to climb" in terms of belief. The default position of Australia players would appear to be dauntless self-confidence but recent drubbings must have eroded that a little.

So Australia are in transition and South Africa are reeling from the loss of several top players. We know that Pakistan - the most recent winners of a global 50-over trophy - can never be discounted, but perhaps it is India who offer the most obvious threat to England's dreams. Which means the ODI series between the teams in July should be intriguing.