Hello Sandman
Is your disco a 200 if so check the fusible links on top of your drivers wing under the bonnet, there are four wires coming from the live side of you battery, for some strange reason are rapped in some kind of bag and this lets the wires corrode I hade problems with headlights going out if I piped my horn or the radio died if I flashed my lights. One word of warning if it is them don’t play with them unless you can join them up again because as soon as I touched the wires they snapped.
If it’s a 300 I don’t think they have the same wires? Perhaps land rover sussed the problem out.
All the best
Arightpest