I've seen the Kidderminster Gypsies on many occasions. They're often camped on the grass verges in Chaddesley Corbett - maybe they do some work at the chicken farm there.
Proper Romany Gypsies in a proper Romany caravan, with at least four horses grazing on the (very wide) verges and fires lit outside their van.
As you say, there one day, travelled on the next - and not a bit of litter or rubbish left behind.