Got the seat back finished this afternoon - wasn't quite as bad as the base.
Quite a bit of gunk came off with the gliptone -
There's a large gash on the top of the seat which needed repair - this is after the canvas repair patch has been glued in. No doubt a professional would have been able to stitch this.
Glue then goes over the patch -
Then filler -
Cracking wasn't too bad on the rest of the seat - very thin coat of filler here after its been applied
Finished seat -
The repair to tear isn't perfect - needs a small bit of flexi filler applied, but it won't be getting any worse anytime soon anyway.