In message
, MIG
writes

On 21 Dec, 15:10, bob wrote:
As nobody has come up with it yet, how about looping the W&C round to
Moorgate, and then extending it to Farringdon.

It's been suggested loads of times. The W & C comes almost to ground
level and would have to go through several important foundations.

Although I've seen that said many times, it must have been possible in
theory as the 1913 Metropolitan Railway Act proposed that an already
authorised line from Moorgate to Lothbury be extended to connect with
the Waterloo and City. Railway No. 5 in the bill proposed extending the
line from Lothbury to a junction with the W&C "at or near the eastern
end of the up platform of the Bank Station on that railway beneath Queen
Victoria Street".

Presumably Lothbury would have been an exchange station for Bank (it's
much closer to Bank than Monument). The following year the plan was
revised to omit the junction with the W&C but instead to provide a
terminus with exchange platforms actually at Bank, alongside the W&C
platforms.

But the problem was, as you say, the shallow depth of the line, which
created much opposition from property owners on the route. So it didn't
receive parliamentary approval.
--
Paul Terry