There were a number of different token exchange designs at various times around the national system.
The GWR one was potentially the most common and possibly the most long lived. Their design catered for both delivery of the "used" token of the Section being exited and collection of the token for the forward section about to be entered.
Deposit/collection of tokens with fixed equipment was both safer - certainly for the signalman - and avoided the train having to slow down as much for the exchange. I don't recall the exact speeds allowed but (don't quote me) I think the exchange gear could be used at as much as 20mph... A speed that no-one would want to make an exchange by hand!
The Llangollen Railway has a very good example at Glyndyfrdwy - just where the passing loop starts on the opposite side of the line from the Box. I have seen this combination of drop-off and collection equipment used. The GWR system included a 3rd part - a large rope net after the collection arm - to catch any token that missed the arm... Clearly a better option than having to search for a token in the lineside vegetation.
When I was a kid I heard a tale of a young fireman who so messed up an exchange that the token (and holder) bounced and flew over the side of a bridge and into a stream... The "culprit" had the task of wading in and retrieving it.
In later years "automatic" token exchange apparatus was fitted at least on some BR locos - There is at least one model of a loco fitted with the gear - I think a smaller Standard Class - ? made by Bachmann?
In 2015 the West Somerset Railway had the ground based gear of a pattern of exchange apparatus at Washford. Slightly oddly this is on the single line through the platform and part way along the length of the platform with no immediate access in either a board crossing or a step in the face of the platform.- however, this did put it very nicely where it could be photographed.
An Electric Token Block (ETB) Block Post at a location with no passing loop is not as odd as it might sound. It acts in the same way as a Section Splitting box on Double Track - enabling trains to follow more closely - that is - it cuts a possibly long single headway into two shorter headways.
It did have to be kept in mind that such an ETB Block Post should not accept a train from both (opposed) directions at the same time - even though the token instruments would be capable of doing this... As proved at (IIRC) Waddon Marsh on the West Croydon-Wimbledon line on one occasion in my experience. (Wasn't me!).
A completely different feature of that route was that, running 2 car EMUs the fairly long level crossings could cause a slow moving unit to become "gapped" on the crossing.
Much more obscurely - where London trams ran on the plough system for power collection a tram could also end up gapped where the plough had to be lifted for one line to cross another... I know this because, according to family legend, my Mum's Dad achieved it and completely jammed up traffic at a junction until a following tram could come along and shove his tram forward to where it could collect powere again.
