This looks like a green and pink noctuoid caterpillar. The one in your photos must be quite young if its only 7mm long and is transparent. Adults can reach up to 16mm long and will have a thin pink line running the whole length of its body.
Many thanks. When I posted this I was not aware just how difficult it would be to identify. At first I was sidetracked into thinking that it may be a cabbage looper but on counting the legs and pro-legs - 6-8-2 - I realized that you could be right. I have about 10 of these now and they are growing fast. Will post again when they have turned into chysalids and again when they have reached the adult stage. Waiting to see if the pink line appears. The biggest is almost an inch long now. Pictures later. Actually my estimate of length was wrong and I have edited the post to read 14mm.