Confidence: I'm as sure as I can be.
Notes: There is always a temptation to ID plants having this general jizzas S. x urbium (S. umbrosa x S. spathularis). And indeed that may be the correct ID in this case. But, from the photograph I don't think one can rule out the other obvious possibilities - S. x geum (S. umbrosa x S. hiusutum) and S. spathularis.
The shape is potentially right for any of these and so one would want to know details of the pubescence and width of the cartilaginous margin of the leaf laminae. S. spathularis is hardly hairy at all, and has the margins of the laminae 0.1mm. S. x geum is hairier (it normally has a few hairs on the laminae themselves)and the margin is wider - 0.2mm. S. x urbium is unfortunately very similar but has shorter petioles than s. x geum and does not have hairs on the laminae.