This little moth is still thought of as a rare migrant to the south coast of England in most literature. This species was first recorded in the UK in 1993. Locally it seems that it has possibly colonised. Although this is only the sixth I've caught (one in 2003, three in 2006, one in 2007 and this one), Nigel Jarman, at Kingdown, catches it more regularly, and has already caught four this year.
It is unlike any other British species and quite distinctive and has a wing span of 20-23mm.
The larvae feed, like other species in the Evergestis genus, on Brassicaceae, especially garlic mustard (Alliaria petiolata) and hedge mustard (Sisymbrium officinale).
Much more common is the Plain Silver Y. The photo doesn't do the "shiny" cells justice, and I think the name "plain" is rather derogatory for a stunning animal.
I don't know why but I really like the pattern on the moth, and the front end always reminds my of one of those big Citroen DS's (also known as Déesse, or Goddess), s of the 1960's. The Broad-bordered Yellow Underwing often stays complete still until touched, but then it flies off in an explosion of bright yellow underwings, with of course broad black borders.