A couple of things: If using MS Word or something similar; set your spell-checker to English: UK and run through all the dialogue by the character, so that your spellings reflect the nationality (I thought of this from what crescent said). ie. programME, coloUr, mUm, etc. etc. and 'yes' rather than 'yeh' dominates too (I think - at least from my experience with brits) ALSO Is your character in a familiar environment (ie. does everyone around him/her have a similar accent)? I presume not, as there would not be much point in conveying accent apart from in initial descriptions and setting (and indeed using the UK spellings, etc - subtleties). If this character is in a foreign environment, you can occasionally mention, or preferrably show over the course of the story, how they pick up the local lilt, or regional phrases, etc. -when you're exposed to, or more correctly immersed in, a culture you tend to unwittingly pick up small mannerisms and characteristics...all subconscious! Just ideas...my >>1c<< worth you could say(not that we have those coins in Australia any more anyway!)