The LNER Encyclopedia

Does anyone know whatever happened to the original 1955 Potters Bar s/box panel after it was replaced by an NX panel in the early 1970s. I did hear back in the summer of 1979 that it was placed in storage by British Rail in Leyton S&T depot near Temple Mills in East London?. Did the panel find it's way to the NRM at York (and placed in storage) or has it been 'lost & forgotten' about years ago?. During the summer of 1973 to supplement my illustrious wages as a 'telegraph lad' at Welwyn Garden City s/box of £8.50p per week i did a bit of overtime cleaning in Potters Bar s/box on a Sunday morning for a couple of hours at which time the aforementioned NX panel was in stiu.

This bit lurks in my collection...

http://richard2890.fotopic.net/p53659724.html

This would have been changed quite early as it shows double track to Greenwood.

I can't remember the exact year now but sometime around 1970 or 71 there was some track & signalling alterations at Potters Bar probably about the time that the original panel was replaced by the NX panel. A (turn back?) siding situated between the down fast and down slow lines was removed and the down slow line was then slewed over towards the down fast line amongst several other alterations that was carried out. Also a 2-aspect 'Intermediate block home' signal was installed on the down slow line near Hawkeshead. Micky

The 'proper' panel at PB was also an NX, Micky, but of the turn-and-push variety (by Metropolitan-Vickers/GRS, who also did panels at Mile End, Bow Jn., Stratford, Barking, and Faversham, amongst others ; all following on from their add-on small panel at Brunswick Goods (lever frame) box, reckoned by most to be the pioneer NX panel, in about 1939, and which I have seen in 'the Warehouse' at the NRM.).

I reckon it was 1972 at the earliest that the resignalling through Potters Bar was done, needing the track alterations to end up with the layout that's there today (plus the retained Down Siding, since gone), and bringing in the 'relay-room' type NX panel that you must have seen.

That additional IBH signal on the Down Slow (the number PB36 springs to mind, but I wouldn't be sure without it being checked) pre-dated the changeover by a while, and was operated from the old panel.
It must have been wanted as an urgent line capacity increasing measure, achieved by creating an extra signal section.

Being an IBH meant that the working from there to Marshmoor of course remained Absolute Block.
I suppose that meant less abortive new signalling work in providing the signal than track-circuiting right through from Potters to Marshmoor, when everything would be 'all change' for the resignalling soon enough anyway.
I think the new signal must have been put in parallel beside the long-established Down Fast 'Auto' signal M28 around 200 yards south of Brookmans Park station, roughly where Hawkshead box must have once been. This could also have then meant that a stopping train might have just gone clear of the new signal's overlap on arriving in Brookmans platform, and the next one could then have PB20 signal about 0.5-mile north of Potters Bar at 'Randalls' (by the Merit factory), cleared for it.
Before the new signal, Hawkshead on the down was one of those locations with a colour-light on one road and nothing on the parallel one. So if a driver was running his train towards there on the Down Slow in the dark when a train had not long gone by on the DF, the driver could get first sight of M28 at red and have to have the confidence that it didn't apply to him so he could carry on in the blackness at line speed. Once he could see that the red was going to pass him on the right, he'd be extra reassured that he was correct.