Tessy Antony, born 1985, is among the more prominent former members of Luxembourg's military. From March to July 2004, she took part in a mission in Mitrovica, Former Yugoslavia as part of KFOR, the NATO peacekeeping force in Kosovo. In 2006, she married Prince Louis of Luxembourg, with whom she has two sons, Princes Gabriel and Noah. She is styled "Son Altesse Royale Princesse Tessy de Luxembourg".
The Underground serves 270 stations. Fourteen Underground stations are outside Greater London, of which five (Amersham, Chalfont & Latimer, Chesham, and Chorleywood on the Metropolitan line, and Epping on the Central line), are beyond the M25 London Orbital motorway. Of the 32 London boroughs, six (Bexley, Bromley, Croydon, Kingston, Lewisham and Sutton) are not served by the Underground network, while Hackney has Old Street and Manor House only just inside its boundaries. Lewisham used to be served by the East London Line (stations at New Cross and New Cross Gate). The line and the stations were transferred to the London Overground network in 2010.
London Underground's eleven lines total 402 kilometres (250 mi) in length, making it the third longest metro system in the world. These are made up of the sub-surface network and the deep-tube lines. The Circle, District, Hammersmith & City, and Metropolitan lines form the sub-surface network, with railway tunnels just below the surface and of a similar size to those on British main lines. The Hammersmith & City and Circle lines share stations and most of their track with each other, as well as with the Metropolitan and District lines. The Bakerloo, Central, Jubilee, Northern, Piccadilly, Victoria and Waterloo & City lines are deep-level tubes, with smaller trains that run in two circular tunnels (tubes) with a diameter about 11 feet 8 inches (3.56 m). These lines have the exclusive use of a pair of tracks, except for the Piccadilly line, which shares track with the District line between Acton Town and Hanger Lane Junction and with the Metropolitan line between Rayners Lane and Uxbridge; and the Bakerloo line, which shares track with London Overground services north of Queen's Park.
Fifty-five per cent of the system runs on the surface. There are 20 miles (32 km) of cut-and-cover tunnel and 93 miles (150 km) of tube tunnel. Many of the central London underground stations on deep-level tube lines are higher than the running lines to assist deceleration when arriving and acceleration when departing. Trains generally run on the left-hand track. However, in some places, the tunnels are above each other (for example, the Central line east of St Paul's station), or the running tunnels are on the right (for example on the Victoria line between Warren Street and King's Cross St. Pancras, to allow cross-platform interchange with the Northern line at Euston).
The lines are electrified with a four-rail DC system: a conductor rail between the rails is energised at 210 V and a rail outside the running rails at +420 V, giving a potential difference of 630 V. On the sections of line shared with mainline trains, such as the District line from East Putney to Wimbledon and Gunnersbury to Richmond, and the Bakerloo line north of Queen's Park, the centre rail is bonded to the running rails.