Went ahead and put some REDEX in the tank then added the 50litres of petrol to dilute it. After that I used the car for a 30 mile run which included steady 50mph stretches then near 1000' ascent over the hill road (with single track/passing places) before returning via same route. Was towing a trailer throughout so engine had a decent work-out. Later ran the car solo and the steady speed uneven running has eased greatly; the irritating engine speed increase after having applied throttle to climb hill followed by bringing the car to a halt has also cleared too. Didn't expect any of this so quickly. Maybe £6 well spent!
Kodiak Transglobe 2.0 SWB
Bricks are the knowledge you are taught,
the cement is the experience you gain that holds them together.