On 20 Sep, 18:41, BRB Class 465 wrote:
The general opinion amonst the fanshafting mafia is that Shaft 4
disappeared in its original form fairly recently. However, it is
possible there is still some form of opening, but cleverly concealed
at surface level. It's very visible down below, however.

I forgot to mention, you might like to ask a certain rather large
person about this, though you won't get a straight answer.