Price of a Mars Bar in 1975?

[lockhart flawse]

By any chance can anyone remember or even know (as in "know" not "think it was about") what a Mars Bar cost in 1975? I remember paying 4 and a half pence for one at the school tuck shop but it might have been a bit earlier than 1975.

L.F.

[fatboy b]

6p in 1971 apparently.

linky