Car not starting

Hi everyone,
We recently bought a Discovery 1 300TDI (automatic) from 1996 for our travels in Australia. The car had been serviced just a few weeks before we purchased it, and even had a new battery installed.
After a month we started noticing that it sometimes would take a few tries to start the car with the ignition. An intermittent problem that gradually got worse. No other problems whatsoever. Then suddenly it didn't start at all and we noticed slight burning smell in the cabin. When the ignition is engaged the lights in the display dim slighty and the starter motor does not turn. We tried installing a new ignition, but that wasn't the problem.
There is no spider - we already looked. The car is not EDC. We can hear the starter relay clicking when turning the ignition. The battery is fully charged.
Any clues? We have not previous experience with Land Rovers so would appreciate any help we can get.
Thanks!

First thing would be to check properly your main earth and live cables, clean and replace if needed.
A burning smell possibly indicates a burned out cable somewhere.
Might even be the starter motor itself at fault, can you easily take it out and get it tested?

Earth cable goes from battery negative to body then chassis all in one cable, they are pretty poor.