The Government Says

'...We the undersigned petition the Prime Minister to Remove the fixed date of 1972 to qualify as "historic vehicle" and make the qualifying date on the vehicles 25th birthday.' -- Dermot Bell

Vehicles classed as "Historic vehicles" must have rolled off the production...

http://petitions.pm.gov.uk/Historic-Car-Tax/

seen at 17:13, 9 August in Number 10 E-Petitions - New Petitions.

TGS