My experience has been that there's this massive cliff - if you can get into a company that's got a strong US attitude towards Tech salaries you can 2-5x your salary. That basically means do the same job but work for either a FANG style company, or work in some parts of Finance (easy to do in London). Someone of my experience (10 years exp) working in an average software company in the UK is probably earning 50-70k. By moving into Finance I'm now doing the same job for closer to 400k,and I'm not paid incredibly well compared to my US counterparts. It's just absurd.