I was reared on the keyboard but my sons were left to their own devices musically. They are self taught guitar players. The latter is a much more difficult instrument . String length and thickness same as for the piano is the principle that underlies pitch and octave.
The difficulty with a guitar compared with piano keyboard is the latter has octaves all laid out to hand, whereas with a guitar you have to know how to select your octave.
To think that London, or anywhere else for that matter, does not belong to any one demographic