The Rise Of The Meal Deal
Sandwich, snack, drink, £3.
A fixed-price lunch combination that became a national institution and a genuine economic indicator.
The optimisation strategy (picking the most expensive possible combination) is practised by essentially everyone and openly discussed.
Price rises to £3.40, then £3.60, then £3.90 each made the national news, which tells you how seriously it is taken.
Cost back then
£3
Goes for now
£3.90–£5, depending where you go