The 136 was introduced on 7 August 1966 *, running from South Harrow Station to Harrow-on-the-Hill, using a single bus (usually RF421) from Harrow Weald's two-bus allocation.  The route provided a service for the first time up the hill to Harrow Village and Harrow School.  In this form, the service ran Mondays to Fridays until 28 November 1969.

The service was extended from 29 November 1969 to Harrow Weald Red Lion, with a Saturday service added over the new northern section.  The southern section received a Saturday service in May 1971, 10 weeks before the route was converted to MBS operation in July 1971.  Further details of the 136 here.