grey or gray?

When I posted recently about Tennyson's poem 'Break, Break, Break', I referred to 'cold grey stones' in my post title.

But I did notice that the word was spelled gray in the poem:

Break, break, break,
On thy cold gray stones, O Sea!

So I started to wonder - as apparently many have before me - whether one spelling is preferred over the other. I thought the British and Australians used grey and Americans used gray.

It seems both are acceptable.

If you search for gray in the Macquarie Dictionary (Australian), you read: 'adjective, noun, verb. Chiefly US' and the entry refers you across to grey.

A Wikipedia entry says

The first recorded use of grey as a color name in the English language was in AD 700. Grey is the British spelling, whereas gray is the American spelling, though the latter was also in common usage in the UK until the second half of the 20th century, and the former is considered acceptable by most American dictionaries and is commonly seen in usage, e.g. in the Grateful Dead hit Touch of Grey.

A website called greyorgray - rather specific! - says

There are two acceptable spellings. Gray is used primarily in the United States and other areas that use US English. Grey is used in Great Britain and areas that use UK English.