Three gold stars to Sacha! Thank you, that is the fella - it's definitely a Staphylea and so far colchica looks the best fit. And yes, it was fragrant.

It doesn't seem to be terribly common, I certainly haven't seen one befo although now I am sure I will see them everywhere. Perhaps I'll go back in autumn and see if I can collect some of the seeds, I'd quite like to grow some of my own.

Thanks again,
Rachel