Before revision: The Circle, District, Hammersmith & City, and Metropolitan lines are services that run on the sub-surface network that has railway tunnels just below the surface and built mostly using the "cut-and-cover" method.
After revision: In London, the Circle, District, Hammersmith & City, and Metropolitan lines are services that run on the sub-surface network that has railway tunnels just below the surface and built mostly using the "cut-and-cover" method.