In this situation there were two pedestrians walking towards me on my side and a rider coming towards me on their left (i.e. all above board and HC).
Where I went wrong was not thinking past the first ped, who I gave plenty of space then found myself faced with the oncoming rider and second ped at roughly the same time (rider slightly closer), and as I had given first ped so much room, I had to move in and then out for the rider, causing ped #2 to momentarily have a cyclist bearing right at him (rather than steadily moving out).
The correct thing to do would have been to slow even more, or stop, as I was still going too fast for this situation (evidently). I've found on the canal that literally stopping can be a good strategy, for all it risks the pedestrian stepping towards the middle of the path and getting the oncoming rider's bars in the back.
I didn't apologise at the time - too busy steering and then I was past. Hence the public apology here, not that it's very likely to be read by the relevant person.
(On the dog front - I'm still collecting footage of negligent dog walkers for a searing video expose. "Brilliant" example yesterday when a pretty large beast jumped out of thick bushes and got a full skid out of the approaching rider. You'll be pleased to hear that I didn't chime in with "nice lead" although I was agonisingly tempted.)