On The Buses follows the fortunes of jack-the lad London bus drivers Jack Harper (Bob Grant), Stan Butler (Reg Varney) and their nemesis, Inspector 'Blakey' Blake (Stephen Lewis). Jack and Stan are a couple of likely lads who enjoy doing what most young lads do--watching girls and getting into scrapes.

However, their lot is complicated by the fact that Stan lives at home with his mum and frumpy sister Olive (Anna Karen), who plague his every turn. Furthermore, Blakey--with his catchphrase 'ooh I 'ate you, Butler'--is forever at their shoulder ready to scotch any designs they may have on anything but driving buses.