Cook has given up the Test captaincy but, as he said more than once, he is determined to continue playing for England for as long as possible.
Giving up the job he loved so much means he is likely to continue churning out the runs for England for far longer than if he had stayed on in a vain attempt to turn things around.
The humour, the relaxed demeanour, the smile were all signs that the 32-year-old opener was happy with the decision he had made and was looking forward with optimism to the final chapter of his England career.
That smile had disappeared during England’s gruelling, nine-week sub-continental slog at the end of last year.
By the end of a crushing 4-0 series defeat in India, Cook was unusually relaxed precisely, as we now know, because he had already made his mind up on the captaincy.
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Chennai, where England conceded their record Test total of 759-7 declared and slumped to a second successive innings defeat after posting 400 in the first innings, was where it all ended.
As he batted away questions over his future immediately after that final humiliation, Cook cut a weary and resigned figure.
His face was flushed of colour and, perhaps a sign of the stress of his situation, small patches of acne covered his cheeks.
He was relaxed but in a way a marathon runner, physically and emotionally spent, is after knowing his race is run.
Cook, a keen runner himself, knew his time on the captaincy treadmill was over. Now, after taking stock over Christmas before finally pulling the plug, he is at peace again.
He looked it as well yesterday. Joking from the moment he walked into the room, the colour was back in his face, the acne gone and the shoulders, slumped for much of that final Test in Chennai, upright again.
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Unlike the end of previous captaincies, there was no formal press conference, no tears and no standing ovations.
Thanks to building work at the England & Wales Cricket Board offices at Lord’s, the final words on Cook’s four-and-a-half years in the job were spoken in a cramped executive box in the Tavern Stand rather than the usual media conference room. It was an understated, rather staid and utilitarian setting. It was very apt then for Cook.
He will now spend the rest of the month off at the family farm in Bedfordshire before returning to pre-season training at Essex on March 1.
By then Cook will not have picked up a bat in more than two months.
He will also have to wait until July, when England face South Africa at Lord’s, to play Test cricket again.
The obituaries on his captaincy may have been written but, if his demeanour yesterday is any indication, there appears plenty of life left yet in Cook’s international career.