Mystery plug

The only connector that I see fit the shape on your picture is purge control valve on charcoal canister. However wire colours do not match: brown/pink and yellow/orange.
But in this scenario you should be missing connection on purge control valve. Do you miss it?

I dont think so but I will double check later as im at work now 
 

I have nothing dangling out at that side of the relay frame. There is the connector for the inertia cut out but the wires are brown & the connector is different.
The wires being red & black, the historic positive/negative is also odd on an original fitment auxiliary. I think you have a foreigner.
M

I'm wondering if it could at one time have been to connect to a lead, thats no longer there, for an exhaust flap actuator which only existed on some early original exhausts.

The noise flap came along on much later car & it came about due, in no small amount , to another Squad, the Noise Abatement Squad. In all probability this squad would cycle around, hiding behind trees & in hedges, with their noise meters, accusing certain manufacturers under the noise abatement order.
MGR Just bunged up one exhaust until the car got just as far enough away as to reduce the sound pressure level to acceptable amounts, it then opened & the car sped away.
It’s a good thought though.
M

Definitely not that but similar 

My bad, the wires are actually brown / black which is live with ignition & a black earth. Did Japan spec have anything different, my headlights have rover Japan part stickers but I dont have any history for the car to confirm. 
 

1275rob wrote:

My bad, the wires are actually brown / black which is live with ignition & a black earth. Did Japan spec have anything different, my headlights have rover Japan part stickers but I dont have any history for the car to confirm. 
 

Are you sure that isn't orange/black?  Brown is usually much darker.

It does look like orange/black to me too..brown is darker I believe.

Japan is a right hand drive country, so it's likely that the headlights are replacement units, given that the headlights are a commonly replaced part as they're next to bloody useless, I wouldn't mind betting that the headlights are new old stock items reimported back to the UK from Japan.

Could be orange & black tbf. Oh well it will remain a mystery for now & doesn’t appear to be doing any harm. Thank you all for your advice & have a Merry Christmas 

My car is also a 97 build and it too has brown/black & black wires in a 2 pin gray plug
Now the only brown/black wires that I'm aware of are for the engine bay fan, but mine hasn't been connected to anything either and the engine bay fan works, so my best guess it that given both our cars are 97s there by relatively early cars that at some stage there it was planned that there would be extra engine bay cooling that our good friends the bean counters decided late in the stage to delete the extra cooling fan in order to save a few shekels and the wiring plug is still there.
When I have the car back together I must check to see if the brown/black wire is live when the engine bay fan is running. That will pretty well prove my theory correct.