Sacha wrote:
Any chance it could be R. Wedding Day escapee?

Sacha, I think the flowers are a bit too small and the clusters of
stamens not prominent enough for 'Wedding Day', although there's some
similarity. It is also very similar to a lot of species type
ramblers, but doesn't quite match many of those familiar to me. I
think chance seedling/garden escape is probably as close as we'll
get. It's a very nice thing to discover, I wonder what the hips are
like.