dave1 Yes back in the day there would have been a lineman at every signal box. In the old days there were mechanical linemen to deal with point rodding and signal pull wires as well as signal linemen for the electrical side. When power frames began to take over control of interlockings mechanical linemen began to disappear and a new higher grade lineman known as a power signal lineman was created. The organisation of signal maintenance staff then comprised PSL, signal lineman, mechanical lineman, senior circuit installer, circuit installer, point fitter and unskilled staff. That was before my time and I expect I may have missed a grade or two from the list.
When I began my LT service I was a T4E, the grades at that time being AET (formerly PSL) Tech 1S signal lineman, Tech 2S signal lineman (did mostly the linemens donkey work, track shunts, delta spreads, possessions etc), Tech 3M mechanical lineman, Tech 3E (formerly senior circuit installer), Tech 4E (formerly circuit installer), Tech 5M (formerly point fitter), Assistant Tech (assumed to be a circuit installer in training), Assistant (unskilled but assumed to be training to be a Tech 4E or Tech 5M).
Of course I began my LT career with signal New Works where we also had T2M Mechanical Chargehand, T2E Electrical Chargehand and the only lineman grades were 6 AETs spread across the New Works depots by an organisational quirk highlighted in a dispute over permanencies and who paid their wages! There were also locking fitters through signals who were Starred Craftsmen (Shops Grades) and some specialist mechanical trades i.e. Blacksmith and Chargehand Point Fitter.
There were lineman depots at every signal box and interlocking when I began my service, there were also Cable lineman depots, Telephone lineman depots, and later radio lineman depots. In practice the radio lineman depots were usually shared with the telephone maintenance main depots and of course later Tech 1E telephone linemen and Tech 1e radio linemen became Comms Equipment Technicians (CETs). Of course from the rolling stock side there were car examiners all over the railway too.
For my sins my progression through the grades was T4E signals installation, T3/4E signals, Higher Grade Working T2E signals, T3/4E Telephone lineman in training, T2E Communications Installation chargehand, T2E signal training school comms instructor, T2E Comms Installation again, T1E Comms Installation lineman, CET Comms Installation, Class 1 Inspector Communications and then came devolution and I reverted to Technical Officer Comms, then transferred to line signal maintenance in that grade before becoming Technical Officer Signals and Communications.
These days my understanding is that the whole concept of maintenance has changed such that staff are centralised to very few locations. Of course when I began my service we travelled everywhere by train so lots of depots were needed in case of shutdowns preventing staff reaching incidents although it was allowed to go by taxi when justified!
Today staff are line based and centralised (devolution to lines involved the building of new depots on all lines) with the vehicles needed to get around the network and little or no reliance upon the railway for transport. IIRC I first became an LT driver in 1987 and drove LT/LU fleet vehicles and hired vehicles of all sorts for 17 years working on all lines. I doubt that any engineering staff these days will ever have the opportunity tom work across the combine as I did, we also used to do work in bus locations and all rail depots in my time with the telephone / comms sections. Of course Chiswick Works is long gone and Acton Works is a shadow of its former self, the bus garages and offices are no longer part of the organisation.
LT back in the day was not perfect but in so many ways it was better than it appears to be today, once upon a time the whole railway management structure was at Earls Court but today it has become a very fragmented organisation with devolved offices all over London and what I see as an inverted organisation top heavy with management such that every worker at the sharp end costs £100s per hour (I kid you not) to the taxpayer.