I grew up in london and can safely say i've been riding confidently here for well over 25 years (not giving away too many clues about my age). I also run the BUG at the university where I work, so felt that I should go on a cycle training course in order that I practise what I preach... it was incredibly worthwhile and I cannot recommend it highly enough, even for other cyclists like myself who consider themselves competent and confident.
You only look around 25.