Tom Anderson wrote:

Anyway, the upshot of all that is that, with the possible exception of
the far eastern end of the core tunnel, there isn't a geological
constraint on depth. It's clearly possible to tunnel through the Lambeth
Group

First read through this, I misread a "g" as a "th" and was put in mind
of a bunch of bishops argueing over whether women and gay people are
allowed to be bishops.

Robin