Lrd may reply telling you why he thinks it's ridiculous, but then you would have to explain why you think it is a sensible restrictions
Good call.
Firstly the restrictions are in place because they need to ensure that fatigue levels are maintained. The further you live from a depot then the more time it takes to get in and out. Often you see this as 30 mins from the depot etc. This 5 mile radius is the same style restriction.
Secondly, we work a 24hr railway. You need to be able to get into work at any time of the day. 25mins might work when you have transport but what happens at oh my god o'clock in the morning or evening. With this HR have direct experience with what is happening at our Victoria depot. We have staff that cannot get in for the earliest shifts and cannot get home late because the last train/tube has departed. This is a concern when recruiting. Their experience is telling them they need to restrict it.
Thirdly, have you measured a 5 mile radius from Vic ? It's surprisingly huge and encompasses a dense population area. My family is from South London and when I checked the radius they are well within the distance. Knowing that area its got more than a sufficient population to recruit from. A problem with this one is that some TOC's are using a direct radius as you can plot on a map. Generally an 'as the crow flies distance. Some are using route maps to check distance from depot and again, as mentioned, some are using time.
10 miles takes you out to Sutton/Croydon/Bromley/Woolwich down in the southeast and when your pushing that distance then you more suited to a different SE depot. Orpington, Grove Park, Dartford. A potential problem SE then have is that you have a pool you wish to pick from that is better suited and may affect recruitment of their other depots. Having a 5 mile restriction reduces those problems.
Depots aren't always best placed and will affect some candidates more than others and this is very common across all TOC recruitment. It just seems that the London based depots appear more restrictive but when you look deeper they generally aren't.
Just look at the GTR thread. Some got declined because of their distance from depot. This is no different to any other depot tbh.
Hope that helps,
Com.