Regardless of the other permutations in a squad of 13 for Thursday's opening Test of the English season, Cook will bat at number three in place of the injured Michael Vaughan and ahead of incumbent Ian Bell.
Flown from West Indies where he was representing England 'A', Cook, 21, was thrown into the opener's spot for the second Test against India in March after Marcus Trescothick left the tour suddenly for personal reasons.
He responded with a display of astounding maturity against the menacing Indian spinners, scoring 60 and 104 not out to help England fight their way back into the series.
Cook looked the part from the start, using his reach to stifle the spin of Anil Kumble and Harbhajan Singh and placing the ball calmly through the gaps on both sides of the pitch.
Trescothick's return to partner Andrew Strauss, another left-hander to score a Test century on debut, means Cook will bat first wicket down at Lord's.
''Most of the time I have opened but I will bat anywhere for England,'' Cook told a news conference today.
''The only difference is that you can put your feet up when the other two lads go out straight away and you get to watch a bit.
''It's still the same game and I still get to go through the same things to make sure I'm right when I bat.
''If I keep scoring runs then they can't keep me out.'' Cook, described by former England captain and coach Keith Fletcher as the finest young player he had ever seen, showed his class last year with a career-best 214 for Essex against the visiting Australians.
His success in India gives England three left-handers at the top of the order and an enviable range of choices when Vaughan returns later in the year.
Cook's biggest test could be his first encounter with the rubber-wristed Muttiah Muralitharan, a consistent match-winner for the Sri Lankans.
''I haven't faced him before,'' he said. ''He's obviously a world class spinner but there's a lot of people who have played him well in this side.
''It's up to me to go up to them and get what hints and ideas they can give me. Talking to other players worked in India.''