A strange photograph taken from Harpenden's Hollybush Lane overbridge reveals the site of Harpenden Junction. When I visited in 1979 I stood in a very similar spot and photographed the signalbox below with the stump of the former Nickey Line leading off to the left, see....
https://www.ontheupfast.com/p/21936chg/26893057004/harpenden-junction-signal-box Just beyond the trees to the left is the start of the Nickey Line Walk that Andy, Mike and I were to walk the length ending up in Hemel Hempstead.