Posted: 31/01/2016 at 11:53
My guess is that what you've seen is wild prunus and/or blackthorn blossom. White blossom on trees that don't yet have green leaves. I saw several hedgerows and trees with this open in sheltered spots last week - this isn't particularly early.
Blackthorn blossom - prunus spinosa
May blossom is the flower of the hawthorn and doesn't appear until the leaves are out.
Hawthorn Crataegus monogyna .......... May blossom