Michael,
Thanks for this it worked.
I need to have the matte and greenscreened segment move though and this is proving difficult. The green screen part is a model moving from right to left on screen and scaled slightly to fit in with the background footage. However when I applied the move and scale to the new top layer, the matte moved but the girl did not. When I went back a few stages and animated both the girl and the matte (ie animate the spectra matte, write down the position and scale parameters and put the EXACT same numbers into a resize on the new layer to match the movement of the flattened matte) the two don’t move at the same time and double edges appear.
It seems as though the resize and Specra Matte parameters are not exactly the same.
Alex