Classic/Antique Car Repair: Mystery Transmission Switch, drive transmission, mgb

Question
Hi, the transmission on my 1977 MGB has a "switch" / plug on the right or passenger side.   I can't find the part listed in any of my books.  I have found the reverse switch on the drivers side.... but the purpose of this second switch on the other side has me baffled.   Any info is appreciated.

Answer
Right off the top of my head, the only two switches I can think off on the late MGB trannys are the reverse (back-up light) switch and, if your car is equiped with an Over-drive transmission, the "reverse lock-out" switch.  Do you have an O/d transmission?

It is also possible this could be a lock-out for the clutch/ brake  and ignition switch so the car wouldn't start while it was in gear.

Regards,
Brian