Red telephone boxes, "mail rail" and counting post boxes

I posted on Saturday about red telephone boxes, and observed that I hadn't seen a red telephone box for some time. The British Postal Museum and Archive organise occasional walks. This one, on Sunday afternoon, was entitled "GPO London", and took in about 4 miles around the City of London visiting sites associated with the former General Post Office.

I stood beside this telephone box earlier in the day:

We encountered these near the start of the walk:

In close up:

As well as listing, this next one is listed. This is not a joke - it has a little plate inside indicating its listed status:

An unusual post box:

At this point in the walk, we got a bit left behind. Zero thought this too good a photo opportunity to miss:

Different types of posting box run from Type A to at least Type G (yawn ...). However, attempts to make them of steel rather than cast iron seem to have always been abandoned with a return to cast iron. Cast iron apparently survives the attentions of British weather and the local canine population rather better than steel.

"Mail Rail" also used to exist. This was an underground train system for transporting post items between sorting offices. I can't remember exactly the extent of this now disused system - it certainly stretched from Whitechapel to the Post Office buildings in the area of the City of London just north of St Paul's cathedral, and I think it then ran on to Paddington and Euston stations. The tunnels are apparently still maintained, though post is no longer delivered through them. And St Paul's underground station on the Central Line used to be named "Post Office Station" because it served four blocks of buildings used by the Post Office. The British Telecommunications headquarters opposite St Paul's Station now occupies one of the four or five large sites that used to be occupied by the Post Office in this part of the City.

Before the walk, we went to the principle Mass at St James', Spanish Place. Speaking briefly to the parish priest after Mass (the first time I have met him since seminary days), I mentioned that we were off to "count post boxes" in the afternoon .... So if you encounter any strange observations on the ecclesiastical grapevine about a census of post boxes in London, it's all down to me.