Not sure if been said but a few of the top of my head based around the Croydon area which has a lot -
Russell Square to Epsom via West Croydon - X68 then 166
Russell Square to Heathrow via West Croydon - X68 then X26
Crouch End to West Croydon via Russell Square - 91 then X68
Hampstead Heath to South Croydon via Elephant and Castle - 168 then 468
White City to South Croydon via Elephant and Castle - 148 then 468
Parliament Hill Fields to Croydon via Stockwell - 88 then 50
Elephant and Castle to Redhill via South Croydon, South End - 468 then 405
Croydon to Stratford via Lewisham - 75 then 108
Elmers End to Bluewater via Woolwich - 54 then 96
Uxbridge to West Croydon via Heathrow - A10/U3 then X26
Croydon to Euston via Brixton - 109 then 59
Norwood Junction to Kensal Rise via Vauxhall - 196 then 452
Orpington to Horse Guards Parade via Crystal Palace - 358 then 3
New Addington to North Greenwich via Eltham - 314 then 132/161