Solomons’ swallow

I have recently been to the Solomon Islands. In the gorgeous village church,
there was a pair of martins, or swallows without a swallow-tail, with a
small nest on a flouro light fitting on the ceiling that liked to do laps
during the singing of hymns. They weren’t a species I recognised; I couldn’t
detect any white patch on the back or rump, nor any red face. Sorry no
photo. Any suggestions?

Geoff Leslie