of approval. After the Great War, money for investment and maintenance became harder to find, as passengers migrated to the new motor bus services. In the 1930s, The London United and Metropolitan Electric companies purchased a large fleet of modern double-deck Feltham trams, built by the Union Construction Company at Feltham. LUT accompanied this change by introducing electric trolleybuses using twin overhead wires as a cheaper alternative for of its routes in 1931. A Royal Commission on Transport, held between 1928 and 1931, ensured that the tram companies retained complete responsibility for the maintenance of its rails and highway, which was shared with other road users who contributed its wear. But this was accompanied by Parliamentary bills in 1930 and 1933 that set up the London Passenger Transport Board to operate the LCC's existing bus and underground train service and to purchase and manage all of London's tramways. Under the LPTB, there was no new investment in tram services and the maintenance of services became a hot political issue in elections in South London, an area poorly served by Underground trains. The merged tram services were held back from introducing new, quieter and more comfortable track and vehicles, in favour of trolleybus services and tubes provided under the New Works Programme. Although the trams returned gross annual revenues of £850,000 (equivalent to £ in ),, the net surplus was £128,000 (equivalent to £ in ), after costs were taken by the LCC, partly to repay the debt of £18m resulting from the merger. Abandonment At this time, trams were starting to be considered out-dated and inflexible and the phasing-out and replacement by diesel buses or trolleybuses started in earnest around 1935, when a large proportion of the trams and of the tracks and ancillary equipment were nearing the end of their useful life. Replacement continued until hostilities stopped the conversion programme in June 1940, leaving only the South London trams and the routes that went through the Kingsway subway into North London. After World War II, shortages of steel and electrical machinery were cited as reasons for not investing in maintenance, while the LCC reported that the service ran at a loss. On 15 November 1946 the London Passenger Transport Board announced that the remaining trams in London would be replaced by diesel buses, stated as being "eminently flexible and much cheaper". (London Transport Tramways Handbook, Willoughby and Oakley 1972).