My experience of UK pentest rates was that they've stagnated or even gone down over the last 20-25 years.

In the early 2000's banks were paying ~£1000-£1200/day for pentesters from boutiques and when I stopped being in that industry ~5 years ago, it was largely the same or even lower for larger companies that could negotiate day-rates down. Big-4 tried to charge more but that's really tricky when you're in direct competition with boutiques who have more testers than you.

By contrast US rates were a lot higher ($2k+/day) and also scopes were larger. A UK test for a web app could be as low as 3 days (even less for unauthenticated) where the US tended to be 1-2 weeks.

One reason they've gone down is outsourcing to lower cost regions, and I'd guess that LLM/AI automation will accelerate that trend...