Although they're not new to me, I'm not familiar with them and so I was pleased to see another, two nights later in Hertfordshire. It seems to me they are a bit like Brimstones - circling around and not going into the traps.
Two species which did attend in numbers, although not necessarily in good quality, were Archips xylosteana and A crataegana, giving an opportunity of compare and contrast photos:
crataegana is first and xylosteana second. Some text books describe the latter as 'more variegated' - I'm not sure what that means, unless it means 'the xylosteana generally has brighter colours'.