Shortly after introduction in July 2006, the Doxford Clipper was extended to Pallion and North Sunderland and operated a circular route taking in Southwick and the Enterprise Park. It continued until October 2009 when it was replaced by the new Black Cats 36A/36C, at which time the Doxford Clipper was extended to Pennywell instead.
Not sure if it's intentional, but definitely worth a mention. The short 39's are coordinated with 38/238 to offer a bus every 10 minutes at 06/16/26/36/46/56 from Holmeside towards the Ryhope Street area of the city adjacent to Esdale Estate. This is in addition to the existing 9 buses per hour on 39/42 from Vine Place and Fawcett Street.
