The public sector is probably a decent place for a well defined career.

This is a good point. There have a bunch of excellent HN posts about the UK gov technical service. It looks like a good place to work, and, since it is civil service, then likely a good career. I think a lot of HN overlooks working in light & heavy industry. Like: Who is writing software that runs power plants and turbines and ABS breaking systems? There are lots and lots of devs in light and heavy industry. And those companies are old and stable.