Rob,
Generally speaking, the Male and Female Kingfisher take it in turns to look after the eggs during the day whilst the other goes out and fish and protect the territory. Different locations will attract different behaviour patterns, but essentially that's how I understand it.
I'm sure other people will be able to expand / clarify / correct if needed.
Hi Rob
I've been observing them for the last 5 years at Rye Meads. Saw them mating last week. This and other courtship can go on for a few weeks before eggs are laid. Also they have been investigating nest holes, and may not have finally decided yet, though she seems to favour one. Once all eggs have been laid, they will then be incubated and hatch maybe 21 days later. Adults take turns and this change of behaviour is the start of incubation - usually noted. The best activity to watch is when they hatch and the adults feed the young - usually frequent sightings. They fledge maybe 25 days after hatching and only around for a day or less as the next brood is on the go.
Enjoy
Simon
Thanks for the replies. I'll try and get across to Rye meads in the next few weeks anyway.