Several different extensions were planned at various stages: at one time, the tunnel was meant to continue from Charing Cross southwards and eastwards, and tunnels for this were actually built as far as the next stop - Aldwych (now closed). Since the tunnels were completed - although the connection to the Piccadilly was never made, because the Piccadilly Line part of the station closed - Aldwych technically counts as a Foetal Ghost on the Jubilee, as well as a standard Ghost station on the Piccadilly. Not a lot of people know that. They soon will, once I've made it a feature of my play in the next MC World Championship - MUHAHAHAHAHAHAHH!!!!
With the building of the Millennium Dome, the demand for a new tube line shifted more southward and eastward. In particular, there came a demand for a new tube station at North Greenwich. So, the Jubilee connection to Charing Cross was closed, and the line diverted southwards via Westminster and Waterloo to the southern bank of the Thames, reaching Greenwich by way of Southwark and Bermondsey before turning north, re-crossing the Thames (or rather going under it) to terminate at Stratford.
Construction of the new tracks encountered major logistical problems, especially during the tunnelling under the river north of Greenwich, and consequently ran into major unforeseen expenses. Consequently, the extension opened late and massively over budget, rather like the proverbial Dome itself. However, unlike the Millennium Dome, the Jubilee Line Extension has proved to be a valuable asset to the many people who have used it, and remains open, functional and well on the way to recouping the expense involved in its construction.
The initials of this article's author are in NO way related to the acronym for the line - they just happen to be his real initials.