Heres the switch in question , //www.ebay.co.uk/itm/BMC-MG-RILEY-VDP-WOLSELEY-1100-OIL-FILTER-SWITCH-13H-1492-/281063394004?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4170af0ad4&_uhb=1

Mousy

Thanks for the input.  No this is the first Austin Cooper he has worked on he is an American Muscle (V8) hot rod guy.  He loves the Mini and so far any of the issues he has been able to correct.  I will pass your responses on to him.

I think from memory it was an orange light on UK cars green was the turn signal just in case he wants it to work again.

I would say based on this your "car guy" is not much of a 'Mini guy'.

That switch is not oil pressure, it is on the oil filter housing it tells when the filter cartridge is blocked. (green lamp in speedo).
Most folks here in Oz take it apart then plug the housing off if it leaks.
These filter housings were used on Australian cars, not sure if UK used them too. But all NLA now.

I'm not recognizing where that is on thhe engine. The usual location is the hole just above the big nut that hides the oil pressure relief valve in the left end of the motor (looking in the engine bay).

The old way still works as well for photos bigger than 3 M if you are too lazy like me to reduce the size or don't know how to do it. Up load the photo to Photobucket. When you click on the picture a box with 4 file formats appears below and to the right. Click on the last one, IMG code ... a yellow flag should pop open which says "copied". With both the MM message box and photobucket open ... left click on the picture and hold the botton down and drag the picture into the message box. The mouse pointer should have a little flag on it with a "+" sign to show the dragging. 

When you open the box to post a message there is a huge green arrow pointing upwards to the left and above the box with the words "click here to select images".

I have a 63' Austin Cooper (998 cc).  My car guy says I need a oil pressure  switch but not like the one minimania and other suppliers say my car needs.  He said it needs to have 4 screws, it might be the housing.  It seems to be leaking around the 4 screw part, please advise me.  I can send you a pic of what he is seeing but I don't know how to attach it to this post.