Cheers for pointing me to the upholstered part of the seat, it set me looking in a better place. If anyone has this problem in future the seat release levers (1 each side) are accessed from the side of the seat. If you look down between the seat cushion and side pannel you will see a screw holding the side pannel in place. The release lever for the seat is under the seat at this point. It's round in shape and has to be pushed to the back of the car to release the seat clamp. Don't be fooled as I was by the indentations in the carpet at the front of the seat.
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