UK Transport System and How It Compares With the USA - WanderWisdom
The last metro? Crossrail and the uncertain future of urban transit | Financial Times
Britain's Other Underground Train, Tube, Metro Rail Systems, and Networks - Anglotopia.net
The World's Oldest Metro Systems - WorldAtlas
Why do so few cities in the UK have metro systems? - Quora
UK Cities with an Underground Metro Service | Binge Travelling
Going underground: the cheapest, deepest, oldest subway systems in the world – but which is home to its own mosquito? | South China Morning Post
London Underground | subway, London, England, United Kingdom | Britannica
London Underground | subway, London, England, United Kingdom | Britannica
How many cities have underground in UK? - Quora
London Underground: The UK cities with an underground Tube system you might not know about - MyLondon
Railway revolution as 34 new train stations could open across UK - see full list - Mirror Online
Why do so few cities in the UK have metro systems? - Quora
London Underground: The UK cities with an underground Tube system you might not know about - MyLondon
Which UK cities outside London have subway/metro/underground/tube systems? - Quora
Rail transport in Great Britain - Wikipedia
Britain's Other Underground Train, Tube, Metro Rail Systems, and Networks - Anglotopia.net
How many cities have underground in UK? - Quora
Subway systems by the numbers - BBC Travel
Revealed: London's secret underground railway system - CNN Style
British trains 'up to four times slower outside the south-east' | Rail transport | The Guardian
London Underground: The UK cities with an underground Tube system you might not know about - MyLondon
MTR - Wikipedia
List of metro systems - Wikipedia
London Underground: The UK cities with an underground Tube system you might not know about - MyLondon
