I have been unable to identify this huge larva seen recently in a meadow in southern UK. I would call it a 'caterpillar' but the online ID pages don't include it. Other creatures have a larval stage too: many kinds of flies and so on.
It is about 7 centimeters long, and has a spike or sting curved upwards and forwards from its rear end on the left (obscured by grass, but possibly pointing backwards in this photo). It locomotes in typical caterpillar fashion, by undulating its body.
Can anyone identify it?