Hi all,

I have a LHD Disco 1 200TD1, today I went to start her up and Nothing. No instrument panel lights, no windows ,blower or anything. Hazards worked, driving lights , indicators all worked. Checked all fuses including the in line ones by the batteries. Checked the batteries are at 12.7V.
Only thing I noticed was the switch for the rear window heater had been left on.(stupid me) but the batteries are not flat as out of the blue she started up and all was fine until I tried anything electrical. any lights, indicators, wipers and the engine and instrument panel dies and then nothing again until out of the blue she will light up again and start without knowing what I had actually done to get that .I have checked the ground cables and connections are good.
I am at a loss now.
Please, any help at all will be greatly appreciated!
Terry

Sounds like an intermittent connection - either earth return, or (obviously) live - if the earths are ok, then I'd start checking the main under bonnet fuses.....

first thing to do would be to remove the engine bay fusebox by unplugging all the plugs, give contact spray then plug all back firmly cos it might be a contact issue there

Don't bother looking for an engine bay fusebox u don't have one... unless there's been a diy addition. We assume u have a post 1993MY so have the infamous 'fusiable links'.
But u could have an iffy ignition switch, the circuits you're having issues with are controlled by the ignition switch with a supply direct from the battery via one of the fusible links.
So test the heavy 'brown' wire at the rear of the switch for a permant voltage, plus its switching to the outputs to the switch controlled circuits such as a heated rear screen, as the switch could be faulty.
The starter relay which also has a 'brown' from the same fusible link.
Hazards/ indicators work as their supply is on another circuit and another fusiable link.

If the switch is is ok then you will need a 200 series wiring diagram to help u test, they are very straight forward to follow.

... i missread 200TD1 which was also misstyped and considered it 2001 .... @discool is right , see attachment

Although much better to install a 300 series engine bay fusebox fuse box which has replaceable fusiable links plus it has additional positions for six or seven fuses which the 300 uses.
Not ever one has issues, l never had any with them they were installed in the main battery loom when I owner a RRc.