Some of the highest salaries in London for software engineers are for senior developers at Ecommerce companies built on Magento or building Wordpress websites for agencies.

The idea that PHP developers don't get paid much is erroneous, on average they probably do, but the peaks are just the same. I currently earn £70k "hacking" php in Magento and I'm based in Manchester where the cost of living is far lower.

Currently my time is split between JS (node and vue, vuex, webpack for frontend work) and PHP (Laravel), occasionally some Python. Primarily work for clients building single page applications. And yes I use version control and keep up to date with modern specs. Haven't touched WordPress in about 5 years thankfully.