The A2005 was originally allocated to the main route through the centre of Canterbury (Castle Street, Guildhall Street and Palace Street including a short multiplex with the A2 High Street), while the A28 took a more indirect route to the east of the city walls.
The choice of route was a last minute decision by the MOT. The original draft of the A2005 was to run on Station Road and Upper Bridge Street, terminating on the A257 at Burgate. In late 1922, the MOT sent draft copies of classified routes to the local divisional engineers, and the Eastern & Home Counties division said the outer route was more widely used, as it avoided narrow city streets, and hence should take the number of the through route.
Today the route of the A2005 is unclassified and largely inaccessible to vehicular traffic.