"Professional" mechanics

Job done.  Worst bit was getting the bottom hose off.  I also changed the rad cap again as a precaution.  Tested the new and old caps on kitchen scales and the old one took 10lb of force to open whereas the new one takes 6lb.  So there was some overpressurisation as well as slack clips.  Hopefully it's now sorted.

As an aside, 5 litres of blue coolant was only £25 from Pebley Beach Suzuki.  It's at least £38 online.