By 1921 route 15 had been cut back to Ladbroke Grove, extending in the east to Barking and North Woolwich on weekdays.

A Sunday extension from Ladbroke Grove to Acton Vale was launched, and the North Woolwich journeys were diverted to Becontree Heath.

From January 1967 journeys to Kensal Rise were introduced, and in October 1969 the route was suspended between Acton and Kew, being reinstated in 1970.

[citation needed] In May 1985, the route was diverted between to serve Cannon Street and the Tower of London.

[3] On 18 July 1992, the Monday to Saturday service was withdrawn between Ladbroke Grove and Paddington, being replaced by new route 23.

[3] Alexander ALX400 bodied Dennis Trident 2 double deckers were introduced on 30 August 2003 to replace the AEC Routemasters when the route was converted to one person operation.