According to The Independent, this statistic is reported by local media based on the route which runs from Clapton Pond to Victoria bus station, using Transport for London (TfL) bus speed data releases.
Interestingly, the average speed of all London buses across the capital is reported at 14.4km/h, which is equal to a chicken's average speed.
"Many bus routes in inner and central London travel through several congested areas. We’re working with boroughs to develop bus priority schemes which should help protect speeds and reliability," said John Barry, TfL’s head of bus network development.
Barry also confirmed 700 places on 24 routes in 17 boroughs are identified for improvements to reduce congestions.
These are the five slowest routes for London buses:
1- 15H Charing Cross Station - 6.6 km/h
2- 15 Charing Cross Station - 6.7 km/h
3- 100 Elephant & Castle - 7.2 km/h
4- RV1 Covent Garden - 7.2 km/h
5- UL16 Earl’s Court Station - 7.9 km/h