[14] A third scheme for 1902 was the Piccadilly, City and North East London Railway (PC&NELR) which proposed a route between Hammersmith and Southgate.

[15] Although favoured in parliament and likely to be approved, this scheme failed due to a falling-out between the backers and the sale of part of the proposals to a rival.

[16][a] In 1905, some of the promoters of the PC&NELR regrouped and submitted a proposal for the Hammersmith, City and North East London Railway.

[26] It featured the company's standard red glazed terracotta facade with wide semi-circular arches at first-floor level.

Platform and passageway walls were decorated in glazed cream tiles in Green's standard arrangement with margins, patterning and station names in mid-blue.

Seat recesses on the Victoria line platforms were tiled in an abstract pattern by Hans Unger of coloured circles representing a bird's-eye view of trees in Green Park.

[43] The same day, Queen Elizabeth II officially opened the line by riding a train from Green Park to Oxford Circus.

A second flight of escalators descends to the Jubilee line platforms,[52] which are 31.1 metres (102 ft) below street level, the deepest of the three sets.

[25][51] The line had been officially opened by Prince Charles the previous day, starting with a train journey from Green Park to Charing Cross.

New tunnels branching from the original route south of Green Park were constructed, and the line to Charing Cross was closed.

[58] Tunnelling began in May 1994, and improvements were carried out at Green Park to provide a direct passageway connection between the Jubilee and Piccadilly lines, including lifts to the platforms at each end.

[59][m] The project also included the construction of a new entrance on the south side of Piccadilly with ramped access directly from Green Park[59] designed by Capita Symonds and Alacanthus LW architects.

This work and a third lift in the new park-side entrance between the street level and the ticket hall were completed ahead of schedule in 2011.

[62][n] At the same time, Green Park station underwent a major improvement programme which saw the tiling on the Victoria and Piccadilly line platforms and the interchange passageways replaced.

The new park entrance and street level shelter feature artwork within the Portland stone cladding titled Sea Strata designed by John Maine RA.

[62][65][66] To help moderate temperatures in the station, a system using cool ground water extracted from boreholes sunk 130 metres (430 ft) into the chalk aquifer below London was installed.

Unused tunnels under Strand constructed as part of Stage 1 of the Fleet line would be enlarged to accommodate the larger DLR trains.

At around 9:00 pm on 9 October 1975, members of the Provisional IRA's Balcombe Street Gang detonated a bomb at a bus stop outside Green Park station, killing 23-year-old Graham Ronald Tuck and injuring 20 others.

The attack was part of a bombing campaign carried out by the gang and in addition to the death and injuries caused damage to the Ritz Hotel and neighbouring buildings.

[78][79] The opening scene of the 1997 film version of Henry James's The Wings of the Dove was set on the eastbound platforms at both Dover Street and Knightsbridge stations, both represented by the same studio mock-up, complete with a working recreation of a 1906 Stock train.