Thanks everyone.Yes, it was the dash light i was on about.I checked all the wires i could see for any loose ones but they all seemed well connected.Ill check more tomorrow.I'd heard about changes to the MOT to do with towbar electrics but i don't know what they mean.I'm mechanically clueless but i'm skint so i'm having to learn

I only just found out the trailer light was supposed to flash once when indicating when i searched some posts about the light staying on.I don't know how,but i never noticed it flashing before till it stayed on. I've done a search on here and it suggests checking a relay next behind the centre fusebox to see if it "clicks" or not.I'll check it tomorrow and if it doesn't "click" then i need a new relay.
Is that right about a relay being broken if it doesn't "click".