It's quite late in the season for a Holly Blue, but possibly a sign of a partial third brood. (Although I did see, and blip one across the road in the community garden on September 9th a few years ago.)
I've seen very few this year, and this was the first on my home patch. Several Small Tortoiseshell and Speckled Wood on the wing too, on a pleasant Saturday morning.
Later, 7yo, 11yo and myself headed down for our annual visit to the model railway show and then walked along the riverside sculpture trail into Saltaire to catch a bit of the festival. And of course the Saltaire Festival wouldn't be the Saltaire festival without a visit to the the churro stall.