No. There is a law against tunnelling within a
significant area around St Pauls. AFAIK there
is no such law concerning any other building, even Big Ben.

So how did the CLR manage to get their tunnels in then?

They used the Tardis to go back in time, and then built the tunnel before
the law was introduced.

Right. "Rails Through the Clay" says the cathedral Authorities (so
capitalized) "feared that the foundations of the cathedral might be
affected"; and a footnote reads: "The Cathedral had been given
statutory protection against damage from underground tunnels, in
the City of London (St Paul's Cathedral Preservation) Act 1935."

The footnote continues by citing "PRO MT 6/2728 and HO 205/266".
PRO is the Public Record Office and I presume the rest of this is
the numbers of two files there.

The CLR tunnels, of course, had been finished in 1900 -- but they
weren't quite as well aligned as the Yerkes tube tunnels opened a
few years later, and this restricted the size of trains that could
use them. With the 1930s plan to extend the line east and west
(mostly completed after the war), it was decided to enlarge the
tunnels to allow standard tube stock could be used, as well as
lengthening the stations to take 8-car trains.

It seems a reasonable conjecture that the "cathedral Authorities"
were similarly fearful of all this planned tunneling (which actually
happened in 1936-38), and wanted to make sure it was done with due
regard for their building; and that the protective 1935 act was a
response to their concerns. But that part is just my guess; for
all I know, maybe the timing of the act was just a coincidence.
--
Mark Brader, Toronto | "...blind faith can ruin the eyesight--
| and the perspective." --Robert Ludlum

My text in this article is in the public domain.