Is it standard that one dialect is followed over the course of an entire work? There are several parts of my grammar that are influenced by the UK, but the majority of it is of US influence.
I think that as long as you're consistent with the individual spelling of each word, you should be fine. I live in Canada, and know a lot of people who spell 'neighbour' and 'savour', but say 'soda' and 'sofa'.
Think it is quite acceptable in the UK to use a mix - I know my writing has a mix of dialects in it because that is the way I speak.
Speaking of English grammar, if you're looking to be published I'd stick to one or the other. Speaking of dialect-regional language. Then of couse if you have a Scot, a Geordie and an Irish man in conversation then throw in the odd regional word for effect.
I am so totally screwed on this count, because I'm half American and apparently the way I write, right down to sentence construction, is extremely American, but at the same time I use full English spelling etc rules, and an apparently very English vocabulary -- and those are all things people have told me because they noticed the contradiction, not something I'm making up about myself. I'm hoping since I'm consistently like this, I can chalk it up to style, and hope no one notices, but I am aware that I'm too British to write American stuff, and too American to pull off extremely formal British characters. Yay for hiding in non-region specific fantasy worlds! Anyway, if you're wobbling between the two, you're in trouble and should really make sure you're following one rule for everything. Such as, if you like the ou spellings (colour etc) but not the s instead of z spellings (realise etc), that will show up. Just keep the spellchecker on your computer set to the correct language option. I've turned mine to American to write some fiction set there - it hoovered up all my extra Us and stuff.
You should stick to one spelling locale for the entire novel. It's doubtful if an editor will ding you if you use the spelling native to a character in his or her dialogue, but the general rule is that if you can't hear it (assuming an audio conversation), don't muck with the spelling. Inconsistency stands out. If you use labor and colour in the same paragraph, an editor will probably notice it and suspect your spelling ability is flawed. As far as dialect goes, stay true to a character's voice. If your narrator uses UK slang, don't turn around in the next chapter and have him talking LA gangstah. Even if the narrator is not an explicit character, he or she should have a distinct and stable voice.
depends on what you mean by 'dialect'... if you really mean that, then it will depend on who the narrator and characters are and how they would speak... if you only mean spelling, punctuation and grammar, then you should stick to either us or uk usage throughout, depending on which market you're wanting to target... unless, of course, the narrator is clearly one or the other, in which case you'd have to stick to that for the narrative parts, anyway... if you did mean 'dialect' as in regional ways of speaking, then it's not the us/uk market that determines that, but your characters and narrator... in which case, of course there could be differences throughout the ms, if all are not from the same place and speak in the same dialect... does that help any?