Did mine the other week, take out the centre panel, fold down the driver or passenger seat back flat(ish) and lean over. I found my normal Draper Allen keys, with the ball ends gets in on an angle on the back bolts. Reach under and undo the nuts...
Live in Stratford upon Avon, Warwickshire.. just come back to Defender ownership and have just bought a 2000 (W) defender 110 utility which I intend to keep so will be spending silly money on it when funds allow. Need to change the fuel pump so...