Tyre age has never been an issue in MOT's before, so long as they meet all other requirements... don't have age cracks or bulges, enough tread, etc.
I was running a set of 104's over winter last year on original tyres - 2005 or 2006. Good condition all round as they'd been stored correctly for about a decade!
Quite often tyres will sit on the shelf for a year or two before even making it onto a car.