Having some experience in the London startup ecosystem, I think London is a great place for founders and investors, but I really doubt the value proposition for startup employees.

London I think is one of those cities that crystallises how bad the general economic state of the world is, and this has been dramatically more pronounced in recent years due to extremely loose monetary policy and quantitative easing among global central banks which funnels money directly into the financial, insurance, and indeed technology (through VC) industries. Broadly speaking, I think there are three categories of hidden, but segregated nonetheless, socioeconomic groups in London, and this has a dramatic effect on quality-of-life and also general conditions within startups.

- The wealthy owners and marshallers of capital: these are your VCs and investors, as well as everyone else that isn't in tech but are closely related including foreign oligarchs. Some startup founders could probably be categorised in the lower-end of this group, as well as staff at financial service firms (investment banks, private equity funds, hedge funds etc.) including investment bankers and others. Quality-of-life is stellar due to very high compensation and/or acquired wealth.

- Support staff to the above: software engineers including many CTOs fall under this category, as well as people on the lower-rungs of the financial and insurance industries. Quality-of-life is generally good, but you are basically detained under golden handcuffs, and you will never earn the same kind of compensation as the marshallers of capital. Software engineer salaries are generally capped at around £150k if you're a lucky, with very few exceptions (HFT firms etc.). Entry-level salaries start at £30-40k, which is atrocious for a very expensive city like London and you will probably have to flatshare with others to make ends meet.

- Everyone else.

What is important to note here is that there is a very implicit status-ranking in these groups, and software engineers particularly are not respected any where close to the level they are in the United States as they are not considered members of the first group. This, as you can imagine, has very severe effects on the level of compensation and the general working conditions that you can expect as an engineer as you are not deemed deserving of more compensation since you are after all "just an engineer". This is also why stock options and other equity compensation schemes are not as popular in London as they are in the Bay Area. Software engineers are considered support staff rather than integral contributors to the success of a technology business.

This social segregation, as you can imagine, also has effects on the social cohesion of the city, and I think the recent increase of crime in London is a direct consequence of the alienation of the third category of people due to the flood of liquidity from the first category, which drives up salaries for the second group of people (and thereby cost of living in London), and prices everyone else out.

Most of Europe suffers under this kind of segregation, and I presume it is partly a consequence of antiquated social structures that were more prevalent during the 20th century but haven't really modernised to align with the interconnected and meritocratic reality of today. I believe this is the primary reason why compensation for software professionals is so low in Europe compared to the meritocracy of America (but even this is changing with implicit filters such as Ivy League degrees etc.).

Most global cities have elements of this as well, but I feel the divide and indeed social inequality is very pronounced in London and is becoming worse by the year, which is among the reasons as to why I left the city for greener pastures.