[Roger Slater]

I've often submitted poems to British children's poetry anthologies, and I generally conform the spelling as best I can to the British spellings. I even (sometimes) change the quotation marks to single inverted commas instead of double, and I move punctuation marks outside the quote marks (if they're not part of the quote) instead of doing it the American way. But I don't think it matters. It's more a copy-edit sort of thing that editors can change on their own. I make the changes myself just so there's one less thing that an editor needs to be distracted by.