Long delay? Yes, there was only one person manning the office and looking after servicing. Still, we filled up with water and did a washing machine load while we were waiting.
After this I cycled to Southport to pick up a package I'd had delivered to Wolverton (complicated story); then we moved on to just past Crabtree Lane Swing Bridge.
Just before getting the diesel we tied up by the marina and had lunch. As I was untying to head for the service bay a widebeam came out of the marina and turned right to come our way. At the same time a narrowboat came along and overtook the widebeam right next to Jubilee. The widebeam must have waved the narrowboat past as there were smiles, not frowns, as the two boats
I must now find a way to suppress this interference which I suspect is coming up the 12V connection (unscreened and running the full length of the boat). I'll try a small capacitor across the power supply first. I have dozens of such things in a drawer at home; here I might have to buy one. Is there a Maplin in Wigan? I might find out tomorrow.