The ''Charing Cross Railway Company’’, a nominally independent concern instigated by the SER, was formed by an Act of Parliament in 1859. The company’s purpose was to extend the existing London & Greenwich Railway metals beyond London Bridge, to eventually arrive at a new terminus in the West End. This involved forming a 1⅓ mile track bed upon brick arches to carry the line through the densely-populated Borough of Southwark, before arriving at a lattice girder bridge to carry the tracks over the Thames. Construction began in the year of the Act, but trouble was already afoot for the SER. In 1860, the Metropolitan Extension Act was created, which enabled the rival LC&DR to reach the City of London. Hitherto, the LC&DR had been running to Victoria by means of the ‘’West End of London & Crystal Palace Railway’s’’ (WEL&CPR) metals between Beckenham and Battersea, via Crystal Palace and Balham. The WEL&CPR became part of the LB&SCR in 1860, a company which the LC&DR had already entered into controversy with; this concerned the sharing of the terminus at Victoria. Consequently, the aforementioned Act of 1860 not only enabled the LC&DR to construct a spur to the City, but it also permitted a completely new line between Beckenham and Battersea, allowing the company to avoid the metals of the LB&SCR. In response to the LC&DR’s City endeavours, Parliament passed a separate Act in 1861 after lobbying by the SER, which allowed the construction of a northern appendix to the westward extension from London Bridge. This would be about ⅓ mile in length, and connect with the London Bridge to Charing Cross route by means of a triangular junction; the SER would now be placed firmly in the City, the capital’s financial headquarters.
Construction of the £4 million Charing Cross extension had begun in 1859, the year in which the Act of Parliament received Royal Assent, but building of the City appendix did not commence until the summer of 1863. After extensive building works and the excavation of 7000 corpses (these subsequently being reburied at Brookwood), scheduled services from Hayes and Greenwich (both at the end of terminating branch lines) began running to Charing Cross on 11th January 1864, followed by North Kent and Medway Valley Line services on 1st April, and Tonbridge and Kent Coast trains on 1st May. The SER’s City terminus site, bordered at its north by Cannon Street, was far from complete, and it would be over two and a half years later until this was commissioned. To span the width of the Thames between Southwark and the City, a 706-foot long iron girder bridge was erected on a series of cast-iron columns, these in turn being built upon brick and concrete bases. The bridge was designed to carry five parallel lines; on the immediate approach to the station, a further four tracks were spouted, and in total, eight platform faces were to be in use. Of the nine tracks, one was to be used for carriage berthing – this lacking any passenger access – and the longest platform faces would measure some 721-feet. The SER commissioned ‘’Cannon Street’’ station for passenger use on 1st September 1866, and without doubt, the entire layout was far more impressive than the efforts of the LC&DR, which had established itself half a mile to the west. A semi-circular-shaped curved overall roof, measuring 680-foot by 190-foot, graced the platforms, this being constituted of a 1000 ton iron framework. Two thirds of the frame’s three acre surface area was glazed. The huge trainshed, which was an enlarged (and, as was later discovered, more robustly built) version of the example which had appeared at Charing Cross, was held up on either side by huge yellow-brick walls. Both trainsheds were products of civil engineer John Hawkshaw. The station’s side walls, some 6½ feet in width, terminated at their respective southern ends in the form of a huge tower, each rising up to 106½-feet above rail level and providing the Thames-facing façade with a spectacular symmetrical appearance. The fact that the station had to be elevated, to reach the level of the incoming tracks, ensured that a huge storage basement, formed of numerous arches, was created underneath the platforms. This was reached by a series of hydraulically-operated lifts, which used water from tanks in the towers as power. These tanks also supplied water for locomotives.
As per Charing Cross, an initially separate commercial entity backed onto the rear of the station, providing a spectacular street-facing façade. This was the City Terminus Hotel, a five-storey masterpiece worthy of Hawkshaw’s station. It was based on the same French Renaissance style employed at the Charing Cross Hotel, and the structures at both termini were designed by architect Edward Middleton Barry. The City Terminus Hotel opened later than the station it served, the first customers using it in May 1867. To coincide with the station’s construction, the opportunity was taken to insert a tunnel underneath the site of the hotel forecourt, for the impending District Railway underground line.
The layout of the entire appendix from the original Charing Cross extension had been geared primarily for a timetable which saw all services to and from the West End terminus call at Cannon Street. Unfortunately, however, the track arrangement derived from such an operating principle would cause congestion chaos in future years, particularly after the discontinuing of the Cannon Street stop. As mentioned earlier, a triangular junction linked the Cannon Street spur with that between Charing Cross and London Bridge. On eastern and western sides of the triangle were three tracks, whilst the southern end of the triangle – destined to become the busiest section of them all – was just double-track. This arrangement south of the Thames was eventually controlled by three signal cabins: Borough Market Junction, Metropolitan Junction, and Cannon Street (No. 2). The station at Cannon Street itself was controlled by a 62-foot long signal cabin which, like the example at Charing Cross, was suspended across the tracks on a lattice girder framework, beyond the platform ends. This had been erected by contractor Saxby & Farmer, a company which is perhaps better known for undertaking signalling projects for the rival LC&DR. The very practice of reversing Charing Cross services into Cannon Street also called for an engine shed to be erected on the southern bank of the Thames. This was positioned immediately east of the Cannon Street approach lines, beside the diverging tracks which formed the east and west sides of the triangular junction. The shed was of a terminating arrangement, featuring five southward-facing tracks (each approximately 125-feet long), which were all fed by a turntable. The cramped nature of the site meant that locomotives would approach the turntable from the north, then after rotation, double-back on themselves to enter the shed.