Think museums, parks, galleries, theatre, exhibitions.

Granted it's not the only city with those, the problem the UK has is that its small, desirable cities are unable to grow or reinvent themselves. Cambridge and Bristol should be ideal for hardware startups, but the cost of both housing and working space is insane for small, provincial cities, partly because NIMBYism and partly because building infrastructure is absurdly expensive when you're constantly having to work around 200 year old buildings and 800yo city plans.

Having kids while living in the centre of a large city is great, as there is so much culture that is aimed at parents and children. When my kid was small we went to museums and concerts and events all the time that were aimed at kids. There were also several different parks, playgrounds, pools and similar activities to choose from all within easy access. Plus once the kids get slightly older they can use public transport to get around and you don't have to drive them anywhere near as much as if you live in the suburbs.