Contracting scales only with the hours you work, so you can’t earn more than a day rate x number of days you work.

You have to leverage capital and/or people to go beyond that.

Yes there's a limit, but with contracting rates reaching 2500 GBP per day (a real life example) I'm fine with that limit.

Contracting in the UK seems to be a sweet gig. It has good tax advantages for the contractor right? And companies like it because it is easier to scale up or down based on need?

Yes and yes. However the government seems keen on making the tax situation worse, introducing new laws which tighten the noose every couple of years, so it's entirely possible that it will get bad in the next 5-10 years. Also, for non-British people, Brexit may make it make it hard/impossible to contract in the UK.

In London it’s good - outside of London not so great

That’s a very good contract- I’m curious as to what that’s for?

Dunno what it's for specifically, I just spoke with a guy who procured such contracts in a large bank.