MTR - Wikipedia
UK Cities with an Underground Metro Service | Binge Travelling
London Underground: The UK cities with an underground Tube system you might not know about - MyLondon
How many cities have underground in UK? - Quora
World's oldest metro systems - Railway Technology
Subway systems by the numbers - BBC Travel
The World's Oldest Metro Systems - WorldAtlas
Why do so few cities in the UK have metro systems? - Quora
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
Does any Indian city has underground metro rail system? If not, why? - Quora
Why is London the only city with a subway system in the UK? - Quora
London Underground: The UK cities with an underground Tube system you might not know about - MyLondon
London Underground | subway, London, England, United Kingdom | Britannica
London Underground: The UK cities with an underground Tube system you might not know about - MyLondon
The power of urban rail - Arup
Britain's Other Underground Train, Tube, Metro Rail Systems, and Networks - Anglotopia.net
Britain's Other Underground Train, Tube, Metro Rail Systems, and Networks - Anglotopia.net
Which UK cities outside London have subway/metro/underground/tube systems? - Quora
This is why Reading and four other Berkshire towns are on the London tube map - Berkshire Live
End London-centric approach and invest £140bn in 11 underground systems, Scape say | Infrastructure Intelligence
List of metro systems - Wikipedia
UK Transport System and How It Compares With the USA - WanderWisdom
Railway revolution as 34 new train stations could open across UK - see full list - Mirror Online
