Big ISPs include BT, Orange, TT, O2/Be etc.
Small ISPs include Zen, IDNet, Newnet, AAISP.
I'm not sure which of those to put Plusnet in.
The
virtual ISPs are the likes of vivaciti, ukfsn, Titan, ADSL24, Falconnet and so on.
Xilo I think are a vISP in these terms but I could be wrong. They certainly do a lot of reselling at the Home level.
People leaving Enta seem to be going to all of the above except Orange.
So maybe you see the reason for my question?