Neil, a regular reader of this blog, saw my tweet and emailed me the following:
Ha ha, your Twitter of 'blikey' reminded me of a derogatory term we'd use when younger... 'gikey' or 'gykey' (never wrote it down, just verbal) which was a portmanteau of 'gypsy' and 'pikey'!
Not the most politically correct of words, and not one I've come across before either. But it does allow for the great exclamation: "Blikey, a gikey!"
(I'm assuming 'gikey' has a 'soft' g sound, as in 'gypsy', but I may be wrong. Any further information on the word would be gratefully received. Oh, I should probably add that Neil – like me – comes from the south of England.)