If anyone can put us out of our misery on the following, I will gladly buy them a pint (or several)!
A mate who is an Army mechanic (so works on a lot of Defenders) replaced the timing belt and spotted that the crankshaft front oil seal was leaking, so he replaced it. In a couple of hundred miles or less it was leaking MUCH worse than before (a regular fast drip that meant I was losing a litre of oil every 100 miles approx.
He then repeated the job (new seal and another new timing belt because the one he had just fitted was contaminated with oil straight away). He thought that it was a faulty seal as the new seal felt a lot tighter when it was fitted. He also cleaned out the crankcase breather pipes (and replaced the plastic breather capsule with a new one).
After 200 miles the oil is leaking out again at a rate of knots -to our complete dismay and bafflement.
We're stuck for ideas as to what on earth is causing the problem, so if anyone can help, we would be very grateful!