SUCCESS !!!
Here is how I did it:-
Drill the top one from below with successive drill bits up to 8mm when I could not get the drill in to the reveal. The top part of the bar has a pointed end, so unless you have a big hole in the centre of the pointed bit you just won't drill it from above. Then put masking tape on the top fibreglass, mark where the pin is using at least 3 angles and pencil marks on the masking tape. Then drill a 12mm hole through the firbe glass, then drill successive holes in 0.5mm increases from the 8mm up to a maximum of 12mm. The bar is 1/2" = 12.7mm, so as your hole will not be exactly central, you end up with a C piece of metal in the hole, which was easy to drift out from above. Only do this if you are having the car sprayed or you are desperate, as the 1/2" hole is ahead of the door mirrors.
With the bottom hole, drill from above with succeesive bits up to 8mm, then drill from below (take the silver sill off, 2 pop rivets and double sided sticky tape held mine in), from 8mm up to 12mm, and drift out the C piece of metal again.
Be very careful when drilling the top hole from below, the metal swarf goes everywhere, and if you are underneath looking up, you will get metal in your eyes unless using protection.
Now with the doors off, and the 4 stubs out, all that was left to do was undo the fittings in the doors top and bottom. 1 came out with the nuts undoing. The other door was so badly rusted, I had to cut them out with an angle grinder.
Next week, I have to drill out the seat rail mountings as the seats are stuck by rust, so under the car, and carefully drill up to cut out the 4 bolts per seat holding the rails to the floor. Then I will have the challenge of getting the 2 pairs of sliding rails apart.
I will post pictures of the rusted pin soon when I can downsize them to 1Mb.