'Cook knew it was time to step aside' - Strauss
Alastair Cook's decision to resign from the England captaincy stemmed from his reservations about "how much he had left in the tank", according to Andrew Strauss, England's director of cricket, who says that the ECB expects to be able to name his successor within a fortnight, ahead of the one-day squad's departure for the Caribbean on February 22.
Speaking at Lord's on the day it was confirmed that Cook, 32, would be standing down from the captaincy after a record 59 Tests in charge, Strauss praised the considered manner in which his former opening partner had reached his decision. The timing of Cook's announcement leaves his successor - almost certainly Joe Root - a full four months of preparation before England's next Test series against South Africa in July.
"This wasn't one of those situations when it was right for me to persuade him to carry on," Strauss, from whom Cook inherited the captaincy back in 2012, told Sky Sports at Lord's. "I've been there myself. You either know if you have got it in you to carry on, or, deep down, you know it's time to step aside.
"He did it the right way. He didn't jump to conclusions, he allowed the dust to settle after the India tour, he took some time to speak to the people closest to him, whom he trusted. I support and understand that decision."
Cook's resignation had been on the cards ever since the tour of India in December, which finished with back-to-back innings defeat for a dispiriting 4-0 scoreline. As he had indicated at the time, Cook chose not to make a snap decision, but instead took the opportunity to take stock before informing Strauss of his intentions when the pair met up in January.
"When the India tour finished, Alastair said to everyone that he'd sit down with me and talk things through," Strauss said, "both the learnings from the India tour and what the England team could do to get better, but also his own position.
"We met up in January and I was interested to see how he had fared in India. I know how draining the England captaincy can be, especially on a long tour away from home when you are on the wrong end of the result.
"So we had a conversation around that, and it was pretty clear that Alastair knew how much drive, determination and energy was going to be required of the England captain in the next 12 months or so.
"He had some thoughts and reservations about how much he had left in the tank as England's longest-serving Test captain, and it was right that we didn't jump to conclusions, and let the dust settle. I allowed him to go away and think further. But, over the last ten days or so, it was clear his mind was made up."
Despite the speculation that has surrounded the role, Strauss insisted that the search for Cook's successor would only now begin in earnest.
"There is a process to go through," he said. "It would have been entirely wrong for me to have spoken to other players about the captaincy before Alastair stepped down, and especially while two important white-ball series were going on in India.
"Now's the chance for myself and selectors, and the coach, to have conversations amongst ourselves and some players in the England environment, to get an understanding of who the right person is, what their philosophy is, and how they intent to take the team forward, so that when we come to announce the new captain, we are sure he's the right man."
Although Root is the outstanding candidate to inherit Cook's role, his lack of captaincy experience is a justifiable concern - he has led in only four matches to date in his first-class career. Strauss, however, played down that aspect of his candidature.
"That is the reality in this day and age," he said. "It's very hard for England players to get a great deal of county captaincy experience. But on one level there's only so much you can do to prepare yourself. I think playing in the set-up for a number of years and understanding the demands is more important.
"[Cook's decision] gives the new captain a huge amount of time to get used to the idea and have conversations about off-the-field stuff with the coaches and support staff, so that when he steps on the field for the first time as England captain in July, a lot of that stuff will already be taken care of."
He added: "Joe has done a very good job as vice-captain. He's matured a lot over the last two years and there is absolutely no reason he won't be one of the strong candidates."
For the time being, however, Strauss preferred to focus on Cook's own contribution as England captain, which included 24 Test wins, two Ashes victories, and memorable series wins in India and South Africa.
"I honestly believe he deserves to be looked upon as one of England's great captains," Strauss said. "I also think the great measure of a leader is what the people who played with you and under you feel about you. I'm certain that there isn't a single player in that dressing room right now who doesn't think Alastair has done an unbelievable job as England captain.
"More than anything, he has had that personal touch. He has shown empathy for people and he's understood just how difficult it can be to play for England. He's had the time and inclination to help people through that. As he walks away he can do so with his head held exceptionally high knowing he gave absolutely everything to the role.
"His record stands for itself as England's longest serving captain and the longest serving one day captain as well. To combine that longevity with his individual performances is a testament to his drive and character. He was certainly never in it for personal glory."
Andrew Miller is UK editor of ESPNcricinfo. @miller_cricket