This is always a little bit of work. Drain coolant. Disconnect coolant hoses. Disconnect hoses for the oil cooler of the automatic transmission. Part radiator from the oil cooler. Remove radiator. Then assemble accordingly.
While the whole lot was in pieces again, I decided to fit a new viscous coupling because the old one had lost its oil filling and looked like this:
and the new one had been delivered to my house from an eBay seller for the precise sum of 1 Euro a few days earlier:
Disassembly/assembly is so easy there is no need to describe it. That done, the car was completed with the "new" radiator in only a few minutes. After all the piping had been connected, it was time to refill the coolant. This was done in true british manner.
The green stuff is coolant, not "Old Speckled Hen"... Tastes differently, too. So finally, a radiator that fits correctly.