This is what I did for my series III the pockets were pretty battered on the inside, and I had to replace the headliner in the XJS coupe, did the headliner. ugh! with what was left, I relined the pockets of the XJ6. I took the pocket off the door card. carefully removed what was left of the fabric in the pocket and used it to make a pattern. Because there was bits of fabric that was missing, I then raided the pantry and used butcher paper and the bits of fabric to make an actual pattern of the door pocket. used craft spray adhesive (the non permanent stick kind), sprayed the bits of old fabric and stuck it to the butcher paper and cut out a pattern on the butcher paper. I then took the butcher paper plastic side up, and sprayed the paper with the craft adhesive; and stuck it to the back side of the head liner fabric pieces.
Busted out the sewing machine rolled the bare edges over and sewn them down to make a nice finished edge. I did the sewing bit because I didn’t want to attempt to peal the leather back and glue the fabric under the leather which was originally stiched in place along with the leather / vinyl. I passed on that bit because I didn’t risk of buggering that up.
I then used the headliner adhesive 3M something and sprayed the fabric and the door pocket (masking off the bits I didin’t want adhesive on) and let it dry, and adhered the fabric to the inside of the pocket. then put it back together with rivets and screws like it was from the factory.