Maybe this is a how long is a piece of string question but does anyone have any idea?
AFAIK, there is not currently any limit on how long a British citizen can stay in Gibraltar (Wikipedia says all British citizens have right of abode in Gibraltar but doesn't give a source; the UK government website just says that British citizens don't need a visa). I assume that once Gibraltar becomes part of the Schengen area the 90/180 rule will apply to British citizens just the same as it would to anyone else, but can anyone confirm?