It's not always the case that the guards compartment coach is always on the tail end, major mainline express trains usually ran with dedicated stock with a brake at each end but some of the more mundane services such as commuter and branch trains might of only had one brake coach and they wouldn't swop brake around for a return journey as they might with a goods brake .
An example is the quin-art sets used out of London's Liverpool St services in pre electrification days two sets used ( 10 cars ) in peak times had the brake at each end but at off peak times they might only use one set which meant the brake would only at one end so coupled up behind the loco during one direction of the route.
The shot below is a bit later than your period but shows how trains could be marshalled.
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Col.