Hi, this single blossom has appeared on my egremont russet tree about 3 weeks after the normal deep pink to white blossom has gone. It is roughly twice the size as the usual blossom and has what looks like curled-up leaves in the centre, I would love to know what it is, tree is around 10 yrs old

It's a rather complex discussion so you can read what the term Phyllody means at this link.
https://en.wikipedia.org/wiki/...