It looks like a ladybird larva. Very good for the garden.

It's a Harlequin larva. They've been spreading from Europe (originate in Japan) - they're like ladybirds on steroids and can outcompete the native ladybird species, so naturalists are worried about the natives dying out.

http://blog.gardenersworld.com/2009/10/28/harlequin-ladybirds/

http://www.harlequin-survey.org/

I note from the distribution maps on the harlequin survey website that they've been found since 2006 in Gloucestershire, with the numbers increasing each year. Harlequins are voracious predators on anything, aphids, ladybirds, each other, you name it.

Ooooo. Beattie they don't sound good. How do you tell the difference between the Harlequin larva and a regular ladybird larva? Are they just bigger?

Have a look at the links I put up and look around via Google. They're bigger, more colourful, fiercer, and so are the adult beetles. Ladybird larvae are mostly black with just a few smaller orange-ish spots. Harlequin larvae are bigger and more colourful. The colouring and markings of the adult beetles is more variable in Harlequins. Have a look here -

http://www.harlequin-survey.org/recognition_and_distinction.htm

I read today that they'd been introduced DELIBERATELY in places in the US. Maybe you didn't have any native ladybirds to lose anyway?

I don't think that would be the case Beattie. There are over 450 species of ladybugs in North America. I've never seen a Harlequin but I have seen lots of other types of ladybird in the garden and at work.

It is commonly mistaken for a garden pest. I had a load of these which i wrote a blog about. The kids where I live used to grab them and squish them, so they were moved in to one particular spot away from the kids, and I saw so many different species of ladybird emerging.

http://www.growsonyou.com/question/show/26069

http://www.growsonyou.com/alextb/blog/10766-update-on-ladybird-larvae

http://www.growsonyou.com/alextb/blog/10948-latest-update-on-ladybird-larvae

Ladybird larvae, well, well, well, doesn't look to friendly to me, and since 1960, no wonder I had not seen it before as I was not around garden wise then, so I must look up all of the references given, thanks to you all Gilli Beattie Alextb for your answers