The parent was often accompanied by another bird which I think was probably a slightly more mature young bird still hoping for a feed.
The best part of a million pairs of swallows visit the UK each year. The Bird Atlas shows that swallows are found across most of lowland UK but are less common in the south east.
The population has increased in the west but declined in the east (and in Northern Ireland).
Overall the English population is stable or increasing.
This graph from BirdTrack shows that swallows arrive in early April and most leave between now and mid October. The red line shows historical data and the blue line data up to last week.