On 19th March 1974, Cannon Street became the first of the ex-SR London termini to have an operational City Travel Centre. The purpose of this was to handle all British Rail queries relating to both domestic and continental services, and it replaced the existing enquiry office which had opened as part of the rebuilt station on 13th December 1965. Such Travel Centres also became features of Charing Cross and Victoria stations in the Octobers of 1975 and 1976 respectively. Further alterations were also planned for Cannon Street, in connection with the extensive rebuilding of London Bridge. On 5th August 1974, the station was closed completely to allow for a re-arrangement of the track layout as part of the re-signalling of the area, and train services did not resume at the terminus until the 6th of the following month. The station was closed yet again between 15th and 20th April 1976, to allow for the re-signalling of Borough Market Junction, a task which also included closures at Charing Cross and Waterloo Eastern. From 17th April onwards, the London Bridge (Eastern) Panel had control of those tracks leading to the ex-SER termini; Cannon Street’s power box had closed on 15th of that month. This whole scheme was followed in 1979 by the commencement of a three year gradual rebuilding of the railway bridge, which produced replacement concrete support pillars and bridge sides clad in corrugated metal.

The 1980s was a decade which witnessed numerous London termini losing their trainshed roofs in favour of office block developments over the platforms. Land values made this a profitable venture for British Rail, and the money made could be spent on modernising other parts of the station. Cannon Street was to be no exception, although admittedly, the terminus was already half way there. During June 1988, the existing V-shaped platform canopies were removed in preparation of the building of a six-storey office block. This would cover the full extent of the former trainshed area, and call for the platforms to be permanently lit. Some of the office block assembly work was completed at Hither Green, and sections were subsequently hauled by train up to the terminus to be fully amalgamated. These works saw the abolition of the track serving platform 1 (the eastern-most surface); the space here was required to house the huge ventilation system, this now being a necessity for the ‘’underground’’ environment. Upon the 9,500 tonne steel-built office block above the platforms, it was also decided to create an open air grass garden area, this measuring approximately 140 feet by 200 feet. Finally, from 22nd July 1991, Cannon Street was closed for exactly two months to allow track re-arrangement to take place as part of the twelve-vehicle ‘’Networker’’ suburban scheme; the ten-vehicle platforms could also be extended at this time to accommodate the longer formations.

On Thursday 5th April 2007, it was announced that a third wave of redevelopment would take place at Cannon Street. The 1965-completed office blocks are to give way to a more modern office and retail development above the northern portion of the station, as part of a £360 million real estate scheme undertaken by the company ‘’Hines’’. Scheduled to begin in summer 2007, the rebuilding programme is planned to take three years to complete, and will create 400,000 square feet of office space, in addition to 17,000 square feet of retail space.