Interviews for the coaching roles – which will be split along format lines – are ongoing at Lord’s after applications closed last Friday. Brendon McCullum, Morgan’s close friend, is among the most prominent names linked with the white-ball role while Paul Collingwood, Richard Dawson and Marcus Trescothick are current ECB employees who could fill the position.

“Whoever comes in on that can’t just be a facilitator coach who is just going to think: ‘There you are, Eoin, all yours. I’ll throw a few balls and do all that type of stuff.’ They’ve got to have one eye on the fact that this team’s got to keep getting better,” Key said.

“Like the Australians would have found when you [Hussain] were playing, everyone’s trying to catch them up. What the great teams are good at is [to] keep evolving. Whoever that coach is has to know – you’ve got the best side or one of the best sides in the world at the moment and you’re a good chance of winning the World Cup, but you’ve got to maintain that and you’ve got to keep evolving with it.

“I don’t think anything is unstoppable. I think if you take it for granted then all of a sudden it sorts of hits you and you don’t realise where that’s come from. What [Australia] did so well is they changed the culture or the mentality of the way they played that game. They focused on that brand of cricket, that mentality, and that’s why it’s lasted longer. We’ve got to keep evolving that.”

Morgan has been England’s white-ball captain since December 2014 but his role came under scrutiny last year following a lean run with the bat which saw him make a solitary international half-century across formats and finish the T20 World Cup with a strike rate of 119.29.

But Key – who first worked with Morgan in 2009 when he appointed him as his England Lions vice-captain on a tour to New Zealand – stressed that Morgan’s future as captain was in his own hands and that he would “do the best thing for English cricket”.

“I’ve spoken to Eoin quite a bit,” Key said. “He’ll always do what’s right for English cricket. He’s pretty clear on that himself. For me personally – and I’ve captained in T20, not at that level – if you’ve got a great captain, which Eoin Morgan is, that’s like playing with 12. As a captain, you impact every game, more so than some of the great, great players.

“You get an overseas batsman to come in and play a T20 franchise [tournament] and he might come off three out of eight times. As a captain, you [make an] impact with your decision-making: every decision you make, within a ball, you will know if that’s been the right decision or not and Eoin Morgan is the best in the world at that. I’m sure at some point, as Eoin will probably tell you himself, if he feels he’s not that then I’m sure he’ll do the best thing for English cricket. He always has done.”

Key also confirmed that he will not stand in the way if England’s new white-ball coach wants to work at the IPL. The ECB have avoided any overlap between England’s limited-overs fixtures and the IPL’s window in recent years and have previously allowed support staff from the white-ball set-up to fill roles with franchises: analyst Nathan Leamon, for example, has spent the last two seasons with Kolkata Knight Riders.

“You have to move with the times, don’t you? At the moment, there’s no international cricket on during the IPL,” Key said. “I would much rather have the best person for 10 months of the year than someone not as good for 12. I would say that it’s a pretty good field of candidates we’ve got and nearly all of them are like, ‘I wouldn’t be going for this if it was one [job].”