The locking mechanism has failed with the door shut, I have removed the door panel and found no problem with linkages. I am assuming this must be an actual lock problem but obviously with the door shut the lock cannot be removed. Does anyone have any solution? i.e. would removing the fuse for central locking enable me to open the door. Thanks.

With power locks, once the system locks, nothing you do electrically will matter. The actuator has to be replaced. Pulling the fuse won't help.
You cannot unlock the door manually with the inside lock knob? If not, you will need to feel around and try to find the lever that unlocks the door right at the lock mechanism.
Once the door is open, replace the failed lock actuator.

I cannot get to it, that's the problem.

I have found in the past the careful examination of the functioning door on the other side will often leave clues as to the inner working's of the other door.
Then, with a steady light and a stiff coat hanger or such, you can reach down from above the latch and undo most any door.

Patience.