Test coach Brendon McCullum says he is ready to be judged on results when he takes charge of England's white-ball teams in a major leadership shake-up.

The New Zealander has reinvigorated England's Test set-up alongside captain Ben Stokes since 2022 and will seek to bring his attacking "Bazball" approach to the limited-overs sides.

McCullum, 42, has extended his contract until the end of 2027, officially taking over the one-day international and Twenty20 sides in January to coincide with a tour of India and the Champions Trophy in Pakistan.

He will succeed Matthew Mott, sacked as coach of England's white-ball teams in July following lacklustre defences of their 50-over and Twenty20 World Cup titles.

"It's going to be an added workload that's for sure, but some bets are worth it, right?" McCullum said at the Oval on Thursday ahead of the third Test against Sri Lanka.

McCullum, who said he had spoken to his wife before extending his contract and enhancing his role, added: "A couple of years ago I didn't have a whole lot of knowledge about English cricket, relationships. But fast forward two years and I've had a great time, I absolutely love being in the position I am in.

"I have a lot more knowledge about the talent that sits in English cricket. Ultimately I looked at the opportunity and thought what a great chance to have a good crack."

England start a Twenty20 series against Australia on September 11 -- just 24 hours after the last scheduled day of the third Test -- and the congested programme demonstrates why they opted to split coaching duties.

Former England batsman Marcus Trescothick will be in caretaker charge for the Australia series.

But the workload is set to become more manageable ahead of the next T20 World Cup in India and Sri Lanka in 2026 and the 50-over equivalent in southern Africa in 2027.

"I think if we look at the schedule, it is easing," said McCullum.

"The last two years would have been impossible, hence we went down the split coaches route.

"Now with it easing -- I say slightly -- it can have one person in the role. We'll have to be smart with stepping (down) players and support staff, including myself, but I don't see it being a problem.

"I'm happy to be governed by results and be in the gun if things don't work out.

"There's opportunities for other coaches to step up and run the team, just like Trescothick against Australia."