Disco 2 Handbrake Switch

Last week, I had a slight issue. To cut a long story short, the Disco was rolling backwards down a slight incline and before I went through someone's fence (which was getting very close), I decided that I needed to stop the Disco. The only way possible was to pull the handbrake on. It stopped instantly. I have since driven the Disco 300 miles and all is well. However, I noticed yesterday that when going up a hill, the handbrake light came on. Once on the flat, it went off. This is becoming a common occurrence. Does anyone have suggestions as to why this might be occurring?

First of all check the brake fluid level cos that warning is for low fluid level too and low level can be sensitive to body position, if the level is OK unplug the resevoir cap's sensor an go for a ride this way, if the warning will behave the same then we know it can be caused by the handbrake switch

Thanks. I will do as suggested. It just seems very coincidental that this issue occurred 5 days after pulling the handbrake on.

Checking the fluid was a good shout - almost down to minimum. Checked it a week ago and it was at max. Prior to incident of disco rolling, I had noticed a slight issue with the clutch pedal. Very occasionally, I would have problems selecting first gear and the pedal did not appear to return. After a couple of pumps it did. Issue is therefore is it a brake or clutch problem? Has anyone any ideas of how best to locate the fault I have bought some more fluid. It is DOT 4. The motorist shop assured me it is correct. hen I read the owners manual, it has lots of letters before DOT 4. Am I OK to use regular DOT 4?

DOT 4 is OK, check if there's no leak at the clutch slave cylinder then, the clutch and brakes are using the same fluid reservoir , inspect at the calipers and any joint on the fluid line to find the leak