I posted a picture here on the forum. They were indeed Tudor
http://forums.doyouremember.co.uk/threads/12774-Crisps?p=167670&highlight=chocolate#post167670
Tudor crisps made them and I believe it would be around 1991 they were marketed as speciel limited edition, and tasted like salted crisps sprinkled with cocoa powder YUCK,
Do You Remember Chocolate Flavour Crisps?
Do You Remember Chocolate Flavour Crisps?