Perhaps the most unusual of the SR electrified lines is the Isle of Wight system. In 1965, the line and its ancient equipment was due for retirement and a strong rumour abounded that the Island railway would be closed, this was substantiated when the Beeching axe fell on the entire Island network. Following the enormous public outcry against the proposal, it was eventually decided to keep open the most heavily used section between Ryde and Shanklin. The BR Board was then faced with the problem of stock replacement as the restricted loading gauge precluded the use of mainland vehicles. About this time, it was found that London Transport (LT) had a surplus of 1920-30 built tube stock. BR was interested, and subsequently purchased around 55 cars, although only 42 actually went to the Island, the remainder were scrapped. Initially, it was the intention to convert these cars to diesel operation using Gardner bus engines, but it was subsequently decided that operation would be more effective if the system was electrified.
The Island electrification scheme commenced in January 1966 and was completed in 15 months. Prior to the LT stock being transferred to BR, it was technically overhauled at Acton Works and then moved to Stewarts Lane for completion, and formed into units of six three car and six four car sets, enabling seven car train formations. Three car units were classified as TIS and formed of Motor Brake Second Open (MBSO), Trailer Second Open (TSO) and Driving Trailer Second Open (DTSO), while four car sets, classified VEC, were formed of MBSO, TSO, DTSO (non-operational) and MBSO. The SR codes VEC-TIS being derived from the Roman name for the Isle of Wight - Vectis. The MBSO cars had a small equipment compartment behind the driving cab containing technical and control equipment, traction power was provided by two 240hp MV traction motors on each MBSO. Total seating on TIS sets was 106 and VEC units 132, with sufficient standing room for an equal number. After sets were formed at Stewarts Lane, testing and training took place on the London to Woking section of the South Western Division, prior to the cars being assembled at Fratton for removal by low loaders to the Island.
The passenger services on the Island commenced from March 20, 1967, and the stock has remained in service until 1989-92, receiving maintenance at Ryde St. John's Depot. When introduced, the stock was painted in rail blue with full yellow warning ends. This remained until the late 1970s when some sets emerged from Ryde Depot with grey doors. In 1982, when no new stock for the Island was foreseen, a light refurbishing programme on the stock was carried out and units so treated emerged painted in blue/grey livery and were adorned with their six figure TOPS number. After the 1980s formation of Network SouthEast, NSE livery was applied to retained stock. Set numbers allocated to three car sets being 031-036 and four car units 041-046; TOPS classification was 486 and 485 respectively. It was unusual for trains to operate in seven coach formation, but four car sets were known, especially on the Ryde Pier Head to Ryde Esplanade shuttle. The sets were finally withdrawn in 1992 when seven 'new' 2-car train sets were introduced, classified 483.

MBSO - 1-25 series