There is a pretty important distinction here -- We have seen in the US consulting market (at large corporations) an influx of 90s style contractor arrangements for staff augmentation. This is basically the counter to failed outsourcing efforts. These contractors almost entirely work for large groups like Robert Half, Tata, Infosys, Tek Systems and others.

We also still have a very very strong consultant labor force making 2-3x what W2 full-time employees can pull in. These consultants generally work through smaller consulting firms that take smaller cuts for the placement/handling billing and invoicing.

I'd classify it into three groups for the UK...

Perm - Mid level benefits + Pay (maybe options in a startup)

Contractor - Individual with their own Ltd company, pays less tax and much higher take home pay but without any benefits.

Consultant - On-site via a supplier on a framework of some kind, however, often a permanent employee of the supplier with the supplier cashing in the margin.

At least 50% of the tech workforce in companies I work with or where peers are at in London are made up of contractors, especially in Banking.

Contractors get paid way more in the US especially on the East Coast because they usually have to take care of their own benefits and taxes