DH and I live in a small, rural market town in 'the Heart of England', having moved out of London over 13 years ago. We still have friends in London who we've known for 20+ years and much longer. Most of them were born and brought up in London, others are not.
Whenever DH or I try to make arrangements to meet up with our friends, they always expect us to come down to London, never the other way round. One of my friends in London, for example, was born and brought up in a small market town but she really likes the big city life. She will suggest a 'day out' including lunch and visits in London because she thinks there is 'nothing to do' in our small town (she has visited once).
Don't get me wrong. I do like London - I think it's a great city - and I go there from time to time, to meet up with friends and see places of interest or to go shopping, but as our friends always expect us to come and see them it feels one-sided, with us always having to spend money on trains, buses and the underground, and taking out time to get to London (which usually turns into a whole day).
Our friends are all in the age group late 40s-60 and none of them have to take childcare into account as their kids are now old enough to look after themselves. Some don't have children. None of them have grandchildren either so I can't see what is stopping them.