If that were true then the UK would have a bigger startup scene than the US? No decent SWE works for less than $200k p/a even if that means going solo (contract/entrepreneur) when facing a devalued local market
I know a few people on ~£140k which is definitely high, but getting much past that is harder. Most mid-to-senior developers I know (in and around London) are on £65k to £120k.
For a regular SWE, $200k (~£160k) is ludicrous for the UK market, but please feel free to offer me a job for that or point me toward the job postings that offer that.
Going contract may be better, but keep in mind you spend time between jobs and chasing leads, and you're unlikely to get a stable years-long contract, especially post IR35 when HMRC will determine you to be a hidden employee (and rightfully so).