UPDATE: Rosy Rustic Moth potato attack strikes again :-(

The only mention there's ever been on the forum is here -
http://chat.allotment-garden.org/index.php?topic=114732.msg1318825#msg1318825

so it seems quite rare, unless we've all just assumed the damage was always blackleg  Not much help I'm afraid 

Just had another couple of tatties destroyed by the killer moth grub 

Here are some mugs shots:

Here's the mothership!

It seems to be a fairly patchy spread and slow onset. I don't think it will have a huge effect on the crop as the potatoes are now flowering. I've probably lost only 1 or 2 full plants so far as the caterpillars seem to just stick to individual stems rather than marauding through the whole plant. I've seen these moths for years now but first time they've affected my tatties. Maybe more than usual survived the winter due to the mild conditions? Happier to deal with these than a dose of blight