This could have been Regent Street. The Greater London Council completed a feasibility study for an overhead monorail public transport system in 1967.
The bucolic charms of Eastcote, as depicted in 1920 by Emilio Camilio Leopoldo Tafani, for the London Underground Group. (Eastcote today: http://bit.ly/2caLZiM)
It is! As it was in 1923, when this Irene Fawkes poster first appeared.