The 141 manages six: Southwark, City, Islington, Hackney, Haringey, Enfield.
Ditto the 176: Westminster, Camden, Lambeth, Southwark, Lewisham, Bromley.
243: Lambeth, Westminster, Camden, Islington, Hackney, Haringey.
It's worth concentrating on Inner London routes where there is a higher...