With my 110 300 Tdi Landrover, traction is frankly c*ap. This is my first landrover and I am unimpressed in the extreme.

I have Avon Rangemaster 750x16 tyres with almost new wear. Today on a flat field in (low range first/second gear with diff lock engaged) which was wettish but not watterlogged, and the remains of summer cut wheat stubble the defender was struggling to cross it. It didn't make it up one very, very mild incline - really just crossing a rutted track into a field which had been rained on. When I tried to go up a slight slope, it stopped at the top and had to be backed down. Pathetic. What's wrong?

 

What Tyre pressures are you running try about 15psi off road to give the tyre a bigger footprint but re-inflate what back on road. Also do not use first gear unless going down a steep hill, better in second or third gear to keep up momentum and reduce wheelspin.

 

A couple of thoughts,
Are you sure the CDL is engaging?
Air pressure is a consideration
Your driving the heaviest Rover made on the smallest tire foot print
I think you need to look at your tire size as a possible problem.
I have seen a fair number of 110's here in the states and seem to do quite well off road.
Mike