It's been quite some time since it's been a colony over here, but just reading the Declaration of Independence or the US Constitution shows how language changes, almost automatically, over the years/decades/centuries. Everywhere you'd see an "s" in a word, they used "f's" in those documents. And it was only one or two hundred years prior to that that the English were using all the thees and thous of the Shakespearean plays and King James Bible. So there seems to be a natural evolution to language.
As for grammar and spelling, I'm afraid they're becoming a thing of the past. There is a whole generation now, who are only learning to spell in "text." R U OK? ROFLMAO, etc. Heck, they don't even teach cursive in primary school anymore.
And yes, Syd, I too noticed that British English always uses the plural collective singular noun. That's very bad grammar over here.
BTW, I live in an area that was a Spanish, not British colony.