Electric services have served London’s oldest terminus since the 20th Century’s earliest years. Only the LB&SCR successfully implemented electric working into London Bridge before the Grouping era, utilising overhead wires rated at 6,600 Volts A.C. However, the wires were installed only for the company’s suburban operation along the South London Line – the main trunk line to Brighton remained untouched (although the system did reach Norwood Junction by means of approaching from Crystal Palace and Selhurst). Six of the whole site’s twenty platforms received wires, these being the southern most surfaces. A London Bridge to Victoria electric service commenced on 1st December 1909, followed by a Battersea Park to Crystal Palace via Balham working on 12th May 1911. Crystal Palace to Selhurst via Norwood Junction was similarly treated on 1st June 1912. The advent of the Southern Railway in 1923 saw the swift electrification of the ex-SE&CR suburban lines with the LSWR-inspired 600 Volts D.C. third rail. Electric services from London Bridge to the termini of Addiscombe, Bromley North and Hayes, commenced on 28th February 1926, followed by electric working on all three North Kent routes from 6th June of the same year. Whilst the presence of third rail spread, the LB&SCR overhead system had, interestingly, seen an extension after the Grouping. From 1st April 1925, it was possible to travel by an A.C. electric from Balham to Coulsdon North, via Selhurst. However, by the end of 1928, this system had been wholly replaced by third rail, Coulsdon North and Crystal Palace being reached by D.C. trains on 25th March and 17th June respectively. It was also in this year that the SR unified the two station sites by knocking a hole into the side wall of the ex-LB&SCR structure, and subsequently installing a second enclosed lattice footbridge. This was undertaken in conjunction with reversing platform numbering, 1 to 21 now ascending from north to south (a 22nd platform appeared with the abolition of one of two rolling stock sidings in-between platforms 13 and 14 three years later). Not content with just completing the electrification of the inner suburban lines, the SR embarked on the installation of third rail along the whole route to Brighton. From 17th July 1932, it was possible to travel from London Bridge to Three Bridges by electric train, a service of which was subsequently extended to Brighton on 1st January of the following year. A trio of ‘’main line’’ terminal platforms had been lengthened accordingly, to accommodate twelve-car electric formations. Mechanical signalling in the London Bridge area and, indeed, up to Charing Cross, had since been dispensed with, colour lights coming into use during 1928 (some of these signals were supported upon redundant A.C. wire gantries of the LB&SCR). A red-brick three-storey high ‘’power box’’ had come into use within the apex of the diverging South Eastern and Brighton lines into their respective stations, on 17th June of that year. Waterloo Junction’s signal cabin was dismantled and shipped over to the Isle of Wight, for reuse at Ryde St Johns Road, whilst another from London Bridge was despatched to Canterbury West, and was suspended across the tracks.
If the station had not been in the thick of a German bombing raid during World War II, we may well still see the graceful lines of the SER’s 1894 station today, and the LB&SCR structures of 1866. Sadly, it was not to be: on 29th December 1940, the 1861 ‘’Terminus Hotel’’ (in use as offices since 1893) was virtually destroyed by bombs, and the adjacent redbrick 1866 façade was also severely damaged. The classic symmetry of the trainshed had managed to avoid the savage of bombing raids, and the ex-SER platforms also escaped with minor damage. The remains of the hotel were demolished, and the LB&SCR façade was ‘’patched up’’, which merely involved blocking up the elegant stone-surrounded windows, not replacing the clock, and installing a very austere and short façade canopy.
During June 1954, the platforms of the through station were extended at their eastern ends by using prefabricated components. This was undertaken in connection with the ten-car train scheme, and BR also took the opportunity to rebuild all other platforms in concrete. The lengthening of the middle island could only be undertaken with the removal of the central track used by cross-London freights – the points of this line were fouling an extension. The loss of this track was, however, trivial, for most such traffic had been using the Nunhead spur over St Johns Flyover since 1929. The Kent Coast Electrification between 1959 and 1962 saw the elimination of steam on the South Eastern Division. Although such traction experienced a sudden cull on the Brighton main line during the SR’s 1930s modernisation, it was in fact the Central Division’s London Bridge station which saw the last scheduled steam-hauled workings. The first saw Battle of Britain Class No. 34070 ‘’Manston’’ power the 03.27 newspaper working to Eastbourne on 4th January 1964. This was followed nearly an hour and twenty-five minutes later by the terminal’s last steam-hauled passenger working: the 04:50 to Tonbridge via the original SER route through Redhill. This was fronted by Maunsell ‘’N’’ Class No. 31827.
Throughout the 1960s, office block schemes were proposed for Victoria, Cannon Street, and London Bridge terminals, the latter two having suffered greatly from World War II bomb damage. As customary for the times, these were uninspiring, and 1961 plans outlined the replacement of the historic architecture at London Bridge with a seventeen-storey high office block, the whole scheme totalling some £4,000,000 (£60,000,000 by today’s prices). Thankfully, this project was thwarted, but the rebuilding of London Bridge was merely put off for a decade. By 1970, land to the west and south west of the trainshed had been sold off for the building of office blocks. The sale of these areas would fund the rebuilding of the terminal and through stations. By 1971, office block construction was well underway, and two years later, construction began on a replacement, and decidedly austere, enclosed footbridge, linking all terminal and through platforms. The lattice footbridge at the eastern end of the through platforms was the first to succumb, this giving over its site to the abomination which was to follow. Of the terminal, platforms 20 to 22 were to close completely, the site of their approach tracks being required for the construction of an advanced signalling panel. The 1866 LB&SCR bomb-damaged façade was completely demolished, and replaced by a purely functional single-storey concourse, which rivalled the trainshed in area. The latter was the only authentic pre-Grouping or, indeed, pre-BR, structure to remain standing. However, even this received makeshift repairs during the works, its roof glazing being replaced by corrugated metal sheeting. All of the delightful SER canopies of the through station were obliterated and replaced by dreary brown tile-clad examples, but six platform faces were retained. In addition to these, an avoiding through track was placed beside the line of platform 6, this being commissioned on 19th April 1976. The London Bridge Signalling Panel first came into use during the Autumn of 1975, it being fully commissioned on 17th April 1976. The then new complex took over the functions of sixteen independent signal boxes in the area, controlling as far as Clapham, East Dulwich, and Anerley in the west, to Hayes, Bromley North, Elmstead Woods, New Eltham, Eltham, and Woolwich in the east (the Dartford Panel taking over thereafter). The new station structures were formally opened on 15th December 1978, even though building work overran into the following year. The transformation of London Bridge was now complete.