It al popped clear to me once I saw that 'Lays' is also 'Walkers'! That's the UK name.

Over here, Walkers crisps in a blue bag are Cheese and Onion flavour. BUT, the bags are dark, Navy blue. What do come in that pale blue are 'Cool Original' Doritos tortilla chips, also made by Walkers, which basically taste like sour cream and chive.

So what you have there are probably potato crisps flavoured with tortilla chip flavouring!