Thanks for the replies chaps......
In the end I used turtle wax bug and tar remover.......worked a treat...
I can't believe some one would paint the whole rear valance which was in good nick, to cover a couple of rusty seams.......
One side isn't even that bad.
The paint underneath is really good..........
Now instead of having a black wavy hand painted line above my rear bumper, I have nice shiney white paint.........
lhd.................