People exit an underground station outside the Bank of England in the City of London financial district in London, Britain, March 23, 2023. REUTERS/Henry Nicholls 

An empty underground station is seen in the early morning hours during a strike called by German trade union Verdi, demanding a wage rise in the public sector, in Cologne, Germany, March 3, 2023. REUTERS/Jana Rodenbusch 

A grate blocks the way to an underground station during a strike called by German trade union Verdi, demanding a wage rise in the public sector, in Munich, Germany, March 2, 2023. REUTERS/Lukas Barth 

People exit Bank underground station outside the Bank of England in the City of London financial district, in London, Britain, January 26, 2023. REUTERS/Henry Nicholls 

A person exits Bank underground station outside the Bank of England in the City of London financial district, in London, Britain, January 26, 2023. REUTERS/Henry Nicholls 

People exit Bank underground station outside the Bank of England in the City of London financial district, in London, Britain, January 26, 2023. REUTERS/Henry Nicholls 

A person enters Bank underground station outside the Bank of England in the City of London financial district, in London, Britain, January 26, 2023. REUTERS/Henry Nicholls 

A man walks and smokes cigarette next to an Egyptian riot police vehicle guarding in front of Metro underground station of Tahrir Square, ahead of the anniversary of the 2011 Egyptian revolution, in Cairo, Egypt January 17, 2023. REUTERS/Amr Abdallah Dalsh 

A rail passenger passes an advertisement promoting cryptocurrency investment at a London Underground station in London, Britain, November 14, 2022. REUTERS/Toby Melville 

Rail passengers sit near an advertisement promoting cryptocurrency investment at a London Underground station in London, Britain, November 14, 2022. REUTERS/Toby Melville 

A rail passenger passes an advertisement promoting cryptocurrency investment at a London Underground station in London, Britain, November 14, 2022. REUTERS/Toby Melville 

Technical devices are seen in a former civil defence shelter, wich provided protection for people for two weeks after a nuclear attack and is nowadays used as a Cold War documentation centre, inside an underground station in Cologne, Germany, October 21, 2022. REUTERS/Thilo Schmuelgen 

A corridor is seen in a former ciliv defence shelter, wich provided protection for people for two weeks after a nuclear attack and is nowadays used as a Cold War documentation centre, inside an underground station in Cologne, Germany, October 21, 2022. Picture taken October 21, 2022. REUTERS/Thilo Schmuelgen 

A dormitory is seen in a former ciliv defence shelter, wich provided protection for people for two weeks after a nuclear attack and is nowadays used as a Cold War documentation centre, inside an underground station in Cologne, Germany, October 21, 2022. REUTERS/Thilo Schmuelgen 

A man enters a former ciliv defence shelter, wich provided protection for people for two weeks after a nuclear attack and is nowadays used as a Cold War documentation centre, inside an underground station in Cologne, Germany, October 21, 2022. REUTERS/Thilo Schmuelgen 

An emergency kitchen is seen a former ciliv defence shelter, wich provided protection for people for two weeks after a nuclear attack and is nowadays used as a Cold War documentation centre, inside an underground station in Cologne, Germany, October 21, 2022. REUTERS/Thilo Schmuelgen 

The door of an emergency kitchen is seen in a former ciliv defence shelter, wich provided protection for people for two weeks after a nuclear attack and is nowadays used as a Cold War documentation centre, inside an underground station in Cologne, Germany, October 21, 2022. REUTERS/Thilo Schmuelgen 

A woman living in the metro station carries her keys as she takes the stairs up from the underground, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, October 16, 2022. REUTERS/Clodagh Kilcoyne 

People exit Bank underground station in the City of London financial district during rush hour in London, Britain, October 3, 2022. REUTERS/Henry Nicholls 

People exit Bank underground station in the City of London financial district during rush hour in London, Britain, October 3, 2022. REUTERS/Henry Nicholls 

People exit Bank underground station in the City of London financial district during rush hour in London, Britain, October 3, 2022. REUTERS/Henry Nicholls 

People exit Bank underground station in the City of London financial district during rush hour in London, Britain, October 3, 2022. REUTERS/Henry Nicholls 

People exit Bank underground station in the City of London financial district during rush hour in London, Britain, October 3, 2022. REUTERS/Henry Nicholls 

An image of Britain's Queen Elizabeth is seen as people wait at Green Park London Underground station, following the queen's death, in London, Britain September 13, 2022. REUTERS/Andrew Boyers TPX IMAGES OF THE DAY 

An image of Britain's Queen Elizabeth is seen as people wait at Green Park London Underground station, following the queen's death, in London, Britain September 13, 2022. REUTERS/Andrew Boyers 

People walk past a screen showing a commemorative image of Britain’s Queen Elizabeth inside Victoria Underground station in London, Britain, September 11, 2022. REUTERS/Henry Nicholls 

People walk past a screen showing a commemorative image of Britain’s Queen Elizabeth inside Victoria Underground station in London, Britain, September 11, 2022. REUTERS/Henry Nicholls 

People walk past a screen showing a commemorative image of Britain’s Queen Elizabeth inside Victoria Underground station in London, Britain, September 11, 2022. REUTERS/Henry Nicholls 

A screen showing an image of Britain's Queen Elizabeth is seen as people walk near Piccadilly Circus Underground station, following the queen's passing, in London, Britain, September 10, 2022. REUTERS/Marko Djurica 

A screen showing an image of Britain's Queen Elizabeth is seen as a person walks next to the stairs to a London Underground station, following the queen's passing, in London, Britain, September 10, 2022. REUTERS/Marko Djurica 

A screen showing an image of Britain's Queen Elizabeth is seen as people walk on the stairs to a London Underground station, following the queen's passing, in London, Britain, September 10, 2022. REUTERS/Marko Djurica 

A screen showing an image of Britain's Queen Elizabeth is seen as people walk near Piccadilly Circus Underground station, following the queen's passing, in London, Britain, September 10, 2022. REUTERS/Marko Djurica 

A screen showing an image of Britain's Queen Elizabeth is seen near an entrance to a London Underground station, following the queen's passing, in London, Britain, September 10, 2022. REUTERS/Marko Djurica 

A screen showing an image of Britain's Queen Elizabeth is seen as people walk on the stairs to a London Underground station, following the queen's passing, in London, Britain, September 10, 2022. REUTERS/Marko Djurica 

A screen showing an image of Britain's Queen Elizabeth is seen from stairs to a London Underground station, following the queen's passing, in London, Britain, September 10, 2022. REUTERS/Marko Djurica 

A woman walks past Southwark Underground station that is closed while London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

A person walks past Southwark Underground station that is closed while London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

People stand outside Victoria Underground station that is closed while London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

People walk past Southwark Underground station that is closed while London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

People walk past closed gates at an entrance to Waterloo Underground station, as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Commuters queue for buses outside Victoria Underground station, which is closed as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Commuters queue for buses outside Victoria Underground station, which is closed as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Commuters queue for taxis outside Victoria Underground station, which is closed as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

A view of closed gates outside Victoria Underground station while people queue for buses, as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Commuters queue for buses outside Victoria Underground station, which is closed as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

A view of closed gates outside Victoria Underground station while people queue for buses, as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Commuters queue for buses outside Victoria Underground station, which is closed as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Two commuters read a sign outside closed gates at Victoria Underground station, as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Commuters queue for buses outside Victoria Underground station, which is closed as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

London Underground workers form a picket outside Brixton Underground station while on strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

People walk past closed gates at an entrance to Waterloo Underground station, as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Commuters queue for buses outside Victoria Underground station, which is closed as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Two commuters stand outside closed gates at Victoria Underground station, as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

A person walks past closed gates at Westminster Underground station, as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

A commuter stands outside closed gates at Victoria Underground station, as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Commuters queue for buses outside Victoria Underground station, which is closed as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

Commuters queue for buses outside Victoria Underground station, which is closed as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

People walk past closed gates at an entrance to Waterloo Underground station, as London Underground workers strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls 

London Underground workers form a picket outside Brixton Underground station while on strike over pay and terms, in London, Britain, August 19, 2022. REUTERS/Henry Nicholls