"Up until the Festival of Britain the area around Waterloo was not well served by public transport. Buses normally kept to the recognised bus stands in Alaska Street or Mepham Street and the trams terminated on a short stub track just short of Waterloo Bridge. If you had to get from Charing Cross to Waterloo you were faced with a walk across Hungerford Bridge and a further 300 yard hike through dimly lit and dirty streets. 
In 1951 this had to change - several million people were going to make their way to the South Bank and various other Festival of Britain sites, and it was up to London Transport to make sure their journey was accomplished in comfort and on time. 
This was not an easy time for London Transport. Considerable damage had been sustained by the system during the war and all of the new RT type buses were either allocated to replace the ageing wartime bus fleet or were being used as part of the continuing tram replacement programme. However, as it always did, LT rose to the challenge, and when the Festival opened on May 4th 1951 they provided not only 8 special services but also nearly 60 back up buses to reinforce the existing services. 
To enhance the traffic flow a new tram layout was introduced at Westminster Bridge and two roundabouts were built at County Hall and Waterloo Bridge. A new bus stand was provided in Cornwall Road alongside The Cut. 
To avoid confusion the 8 special services were given letters instead of numbers and they served the following routes: 

A: Connected the Science Exhibition and the Underground at South Kensington with Battersea Gardens. At South Kensington the buses picked up in Pelham Road and at Battersea the stop was in Albert Bridge just south of the Parkgate Road entrance. Fare was 3d. Six buses were allocated to this route and were kept at Battersea Bus garage. 

B: Connected the Underground at Sloane Square with Battersea. The stop at Sloane Square was in Holbein Place and this then ran through to Queenstown Road and terminated by the Chelsea Bridge entrance to the Gardens. The fare was 3d. 8 buses were allocated to this route and were nominally kept at Norwood Bus Garage. A shortage of space meant that in reality they were kept in a special compound in front of the nearby Norwood tram depot. 

C: Linked the Festival Gardens with the South Bank Exhibition site. The buses departed from a stop in the Prince of Wales Drive west of the Queens Circus entrance to the Gardens and terminated in York Road. The fare was 6d. Altogether 40 buses were allocated to this service and they were split up between the garages- 15 were kept at the Poplar trolleybus depot (although their official designation shows 5 at Athol Street (Poplar), 5 at Forest Gate and 5 at Clay Hall. The latter being of interest in that it was built of the site of the pleasure gardens that once stood at Old Ford.) 10 were kept at Camberwell and 15 were kept at Pecham? - although 5 of these were officially allocated to Catford. 

D. This was part of the river/bus service to Lansbury and connected West India Dock Pier (Manila Road) with Saracen Street. Return journeys to the pier started from Canton Street. The fare was 1.5d and there were 2 buses allocated which were kept overnight at Poplar trolleybus depot. 

E. This gave a connection between the South Bank and both Victoria Coach Station and the Green Line at Ecclestone Bridge by using a terminus on Elizabeth Bridge. The fare was 6d. and 4 buses were allocated from Victora Garage. 

F. This served to connect the large coach parking area set up on Clapham Common near Clapham South tube station with the Festival Gardens (Prince of Wales Drive terminus). 6 buses were allocated from Elmers End Garage and the fare was 6d. 

G. This was a 'Park and Ride' fore runner and provided a continuous linking service between car parks and the South Bank. The car parks served were at Lavington Street (between Blackfriars and Southwark Bridges), Southwark Street, three sites in Blackfriars Road, and Lambeth Baths. The fare between these and York Road was 3d. 4 buses were allocated and kept overnight at Camberwell. 

H. Connected the Festival Gardens car park at Patmore Street with the Festival Gardens (Prince of Wales terminus). A low bridge meant that the nearest the service could get to the car park was Ascalon Street. The fare was 3d. and two buses were allocated from Streatham Depot. 
All of the above services were operated by STL type vehicles. 

One further 'lettered' service was also introduced and this was service 'J'. This was really the forerunner of the Round London Sightseeing Tours which are a familiar sight in London these days. For two shillings and sixpence you could spend two hours on a circular tour taking you "Around the town for half a crown". The service had hourly departures and used the four RT type buses that had spent the previous year touring Europe promoting the Festival of Britain. These four buses RTs 1692, 1702, 3070 and 3114 were based at the Old Kent Road. Three pick up points were provided at Buckingham Palace Road, South Kensington Station (Cromwell Place) and Bloomsbury (Southampton Row). Service 'J' started operation on June 11th 1951 and operated daily from 10.00am to 4pm.

Because of the different opening times of the various sites some of the routes started operation before others. Route D started operation on May 3rd and ran every day from about 10.15am to 9.00pm. Routes E and G started on May 4th and ran daily during the exhibition hours. Routes A, B, C, E, F. and H started on May 11th and ran Monday to Saturday when the Festival Gardens were open. A Sunday service on these routes started on June 3rd. 
With nothing similar to base research on several mistakes were made in the special services that had been provided. One problem was that those who planned the services assumed that visitors would take in more than one of the Festival sites during the day. As we know this was not to be the case and the special services suffered accordingly. Route C was heavily over allocated with vehicles and was reduced from 40 buses to just 12. The competition from the slower riverbus service between the South Bank and Battersea had proved more popular than anticipated and this was a major factor in the reduction of services on Route C. Funnily enough the longer riverbus ride to West India Dock Pier had not proved so popular and from the 4th of June 1951 the route D shuttle from the Pier to Lansbury was reduced at an 'as required' service. 
The route serving the car parks - routes G and H - failed completely and were withdrawn, and routes E and F were reduced in frequency from the 24th June 1951. 
Not all was doom and gloom however, route B from Sloane Square to the Festival Gardens was more successful than anticipated and two extra buses were need to reinforce the service. 
On the closure of the South Bank Exhibition on September 30th all of the remaining special services except A, B and J were withdrawn. A and B continued until 3rd November when the Festival Gardens closed at the end of the season. Both of these special services were eventually introduced with numbers (45A and 137A) and continued in successful operation for many years."