Some sort of blossom

It was my turn to have the car today (we're still one down after last week's theft) so I took the opportunity to pop along to the local nature reserve. This tree really caught my eye, and I'm hoping someone will know what it is!
As it has been a busy day I was still wearing my dog collar, which may have helped the conversation I had with a lovely couple who clearly had more than a passing interest in photography.