So, it was freshly dead, but I'm sure I imagined one of its tarsi twitching. Found by me in strandline of local-origin tidal refuse at Southwold, Suffolk. Publication on its way, but hopefully this will include news of a local population. I'm on the hunt with Howard Mendel in July, so fingers crossed. In the meantime, if anyone chances on the species in coastal Suffolk, do get in touch. It's a stunner.