Cheers for the info,in the end I ground the sealing face of the the nut back on the new switch and fit back with some sealant lights are now working.

I just screwed it back in the hole the old one came from. Tried it with differnt thicknesses of washers. Didnt fancy removing the box to take a look.

I have a disco 1 300tdi manual. The reverse light stopped working so I fit a new one,the switch works when pressed manually and eliminates the lights. Has anyone got an idea as why it wont work in the gearbox and how do I fix. Thought about fitting a new switch that operates off the actual gear...