Lepidoptery (Updated)

Update: Jan has come to the rescue in the comments. It is a Small White, or Small Cabbage White. They're quite common so it shows how much I know about butterflies. Fortunately the only vegetables I've planted this year are carrots.

I love the internet.

It's that compound eye that draws me in. And the fragility.

It landed on the bathroom windowsill a few mornings ago and stayed there long enough for me to grab a camera and take some shots. Then it was gone, fluttering erratically towards the trees on the other side of the road. The photographs are worth clicking to enlarge - the digital camera was on form and I had a cooperative subject.

April's quite early in the year for butterflies. Or is it a moth? After searching reference books and online I've drawn a blank. Medium size, perhaps 50-60mm. Pale yellow wings with a mottling of brown. The closest possibility I've come across is a brimstone.

Maybe there's a lepidopterist out there?

Labels aren't everything, but I want to know.