Baby swallows

Like last year the swallows have ignored the expensive ceramic nests I put up for them in the barn and built their own. I was sure there was a nest there but couldn't find it until the other day. In the gloom of the barn it looked empty but I took a flash photo and can see three young swallows at least. Whilst I was taking the photo a parent flew in and was not best pleased with my proximity to the nest. Given that we have had a decent summer I suspect that this was a second or third brood of youngsters.