There is a temp sensor in a bung in a pipe spliced into the lower rad hose, I am sure this was for the existing electric fan, came to me with the fan hardwired to dash switch.
There is also the switch in the photo in the bottom right side of the rad, facing the grill. What would this have been for as currently no sign of wiring nearby. Can this be used to drain the rad?
For what it's worth I wonder if this Mini originally was an SPI version? The car had a John Cooper Garages Conversion very early on in it's life,
Has a CAT and a plugged bung in pipe behind the CAT for an "EXH" warning light/alarm in a switch panel.
Has remnants of a white nylon/plastic return line from engine compartment to fuel tank, with a one way valve at tank that only allows entry into tank, remnant of 'Charcoal Canister System'?