Prince Charles and Camilla, Duchess of Cornwall, walk through a ticket gate as they prepare to travel on a Metropolitan underground train from Farringdon to King's Cross as they mark 150 years of London Underground on Jan. 30, 2013, in London.
Prince Charles laughs as he prepares to travel on a Metropolitan underground train at Farringdon station as he and Camilla, Duchess of Cornwall, (not pictured) mark 150 years of London Underground on Jan. 30, 2013, in London.
Prince Charles and Camilla, Duchess of Cornwall, prepare to travel on a Metropolitan underground train at Farringdon Station as they mark 150 years of London Underground on Jan. 30, 2013, in London.
Camilla, Duchess of Cornwall, and Prince Charles travel on a Metropolitan underground train from Farringdon to King's Cross as they mark 150 years of London Underground on Jan. 30, 2013, in London.
Camilla, Duchess of Cornwall, and Prince Charles travel on a Metropolitan underground train from Farringdon to King's Cross as they mark 150 years of London Underground on Jan. 30, 2013, in London.
Camilla, Duchess of Cornwall, and Prince Charles travel on a Metropolitan underground train from Farringdon to King's Cross as they mark 150 years of London Underground on Jan. 30, 2013, in London.
Camilla, Duchess of Cornwall, and Prince Charles travel on a Metropolitan underground train from Farringdon to King's Cross as they mark 150 years of London Underground on Jan. 30, 2013, in London.
Camilla, Duchess of Cornwall, and Prince Charles travel on a Metropolitan underground train from Farringdon to King's Cross as they mark 150 years of London Underground on Jan. 30, 2013, in London.
Camilla, Duchess of Cornwall and Prince Charles visit platform 9 3/4 at King's Cross Rail Station during a visit to mark 150 years of London Underground on Jan. 30, 2013, in London.
Prince Charles and Camilla, Duchess of Cornwall, visit platform 9 3/4 at King's Cross Rail Station during a visit to mark 150 years of London Underground on Jan. 30, 2013, in London.
Prince Charles and Camilla, Duchess of Cornwall, visit Platform 9 3/4 at King's Cross Rail Station during a visit to mark 150 years of London Underground on Jan. 30, 2013, in London.
Camilla, Duchess of Cornwall, and Prince Charles visit Platform 9 3/4 at King's Cross Rail Station during a visit to mark 150 years of London Underground on Jan. 30, 2013, in London.
Camilla, Duchess of Cornwall, and Prince Charles, second right, study a model of the refurbished King's Cross Rail Station during a visit to the terminal as they mark 150 years of London Underground on Jan. 30, 2013, in London.
Camilla, Duchess of Cornwall, and Prince Charles study a model of the refurbished King's Cross Rail Station during a visit to the terminal as they mark 150 years of London Underground on Jan. 30, 2013, in London.