My next idea was to lie at the edge of the river (there was a small pebble 'beach' area which made for an uncomfortable place to lie) and camouflage both the camera and me. At least that way it would be a much smaller, albeit unfamiliar, object to the kingfishers but I hoped small enough for them not to worry about.
This did bring them slightly closer as the photos below show, but not what I had in mind for anything decent photographically. Admittedly I'm sure the birds would have gotten used to the presence of me on the riverside and the hide, but I couldn't leave the hide out for fear of other people seeing it and either destroying or stealing it. Nor did I have the time to lie in wait all day every day. So it was on to plan C...