I'm going to caveat this with asking those of you working in London not to answer. Only because it's just different there regarding people in the middle of their career having/not having children...Where I live around 80% of adults over the age of 30 have children (young or adult).
At my workplace (where I am a senior member of staff), I've noticed a tendency for those with children to be dismissive towards, and make comments about the immaturity of those without children. This seems to be regardless of every other aspect of the child free workers lives, including caring responsibilities etc. I would add that those the same age with children do not seem to attract the same negative and condescending attitude.
My AIBU is to those who are childless; have you experienced this in the workplace?
YANBU I've experienced this too
YABU That's not my experience