On May 2, 3:21 am, "John Rowland"
wrote:
gauge, I'm not sure. I do know that the Northern Line north of Highgate was
built to mainline gauge but has since been reduced to tube gauge by lowering
the North Circular Road.

Theres a bridge just north of West Finchley station that is pretty low
and thats been there since at least the late 80s (when I used to
commute on that line), probably the 60s or 70s. The north circ was
widened in the mid 90s when that new lower bridge was built.

B2003