I went back to the "niltava" place this aft - as had been told the bird had dark face/head, which fits niltava but not bluetail. Again, no niltava, but a female or young male bluetail. Email from one of the finders (aka Bjorn n Karin), sticking to their identification as niltava. So, I'll have to try again.
Saw quick flash of blue-tailed skink tail, as the animal vanished by footpath.