Wikipedia inform me that "Prawn cocktail flavour crisps were the second most popular in the UK in 2004, with a 16% market share"
Stats from Daily Record (from Scotchland) which gives a 2004 rundown, as follows:
1 Salt and vinegar 27%
2 Prawn cocktail 16%
3 Cheese and onion 14%
4 Ready salted 12%
5 Worcester sauce 7%
6=Tomato ketchup 6% 6=Bacon 6%
8 Chicken 5%
9 Pickled onion 4%
10 Beef 3%
The Metro, in Feb this year, gave the following dubious list:
(I say dubious, because it puts 'cheese' first, and cheese & onion appear further down the list. The survey was done on behalf of Pringles, who make a cheese flavour, but PRINGLES AREN'T CRISPS! They should have stuck to dodgy jumpers and socks, imho.
1. Cheese
2. Salted
3. Cheese & Onion
4. Salt & Vinegar
5. Hot Pepper/Chili
6. BBQ
7. Beef
8. Fish/Seafood
9. Sour Cream & Onion
10. Lightly Salted