That's not isolated to manuals, my auto one had it as well, the light I believe is actually fuel pump pressure, mine did it for 5 or 6 years, only ever a blip for a second or so, never caused any major problems so I let it be.
Thinking about it, I should still have a reconditioned pump for one in my workshop, air con pump, belts, filters, God only knows what else is on the shelves for it.
yep just a blip, I found the discos more versatile and better everyday driver, but rot like a Jeremy kyle contestants teeth