Baby birds at Dalgety Bay rail station

I don't know anything about birds, but these little ones are swallows or swifts, I think. The nest is perched on top of a girder at Dalgety Bay rail halt, and the four little ones chirp like crazy when the adult birds fly in with food.
I took this one with a compact digital, I'll take my SLR along tomorrow to see if I can get something better.