Snake's Head Fritillary.

I have been seeing blips of these for a while now but ours haven't been showing very well.   They have been in place for a lot of years and naturalised well.  Normally they are a sea of flowers but not this year.

Part of the problem appears to be snails going by the slime trails and nibbled areas.  Fritillaria meleagris is native to Europe and parts of the UK (although some experts question whether it is a long established garden escape rather than native)..