Alresford signal box is the only original Mid Hants box to survive into preservation. It was built to a standard design by the LSWR and was classified by the Signalling Record Society as an LWSR Type 1 signal box. In BR days, the box was equipped with a 16 lever frame and it was still in this condition when the railway was reopened from Alresford to Ropley in 1977. This original frame had two levers that were of the three position type whereby two signals could be controlled from the same lever. When the lever was ‘pulled’, one signal would clear and when ‘pushed’ into the frame, an alternative signal would operate. When the lever was in its mid position, both signals would be at danger. One of these levers has been retained (No.5) and its function is to control two shunt signals – when pulled, it operates a shunt signal mounted on the Down Inner Home gantry to control movements into the station area when the platforms are occupied. When pushed, it operates a shunt signal controlling movements out of the Cattle Dock siding onto the single line.
When the box was re-commissioned in 1977, the method of working the single line to Ropley was One Train Working with a Train Staff. Just one year later, a ground frame was installed at Ropley and it became a Block Post which changed the method of operation to Train Staff and Ticket. This enabled one train to pass through the single line section with a ‘Ticket’ once the Alresford signalman had shown the driver the Train Staff that the signalman retained in the signal box. Once the train had arrived at Ropley, a second train could be signalled through the section but this time with the driver in possession of the Train Staff. This method of working remained in place up to 1986 when Tyers No.12 Electric Key Token (EKT) machines were installed to replace the Train Staff and Ticket working and enhanced the operational capabilities of movements between Alresford and Ropley.
The next major change at Alresford occurred in 1996 with a complete renewal of the mechanical and electrical interlocking. The Stevens frame was also extended to 18 levers of which 17 are in use. This extension to the frame was made to accommodate the provision of the Down Outer Home (No.1) and Up Advance Starting (No.15) signals. This latter signal is designated as the section signal and as such, is electrically interlocked with the EKT machine. This signal cannot therefore be cleared until the signalman has obtained a key token release from the machine. The Down Outer Home signal is 974 yards from the signal box and like all other semaphore signals, is connected to the lever by stranded wire and is one of the longest ‘pulls’ for signalmen on the MHR. A new Down Distant signal was also installed but as this is now 1919 yards from the box, it is automatically operated by an original electric motor when the Down Outer Home and the Down Inner Home to Platform 1 are cleared. As such it does not have its own lever in the frame. Concurrent with these major changes, the original BR(S) Upper Quadrant pattern signalling was converted to LSWR Lower Quadrant signalling.
To further improve the electrical interlocking, two track circuits were installed between the Up Advanced Starting signal and the two platform Starting signals. A short time later both the platform roads were also equipped with new DC track circuits.The most recent change has been the replacement of the From Middle Road Shunt signal (No.14) from amechanical disc signal to an LED Ground Position signal with a route indicator that displays either a ‘1’ or ‘2’ for the respective platform. The Down Distant, Down Outer Home and Up Advance Starting signals are electrically lit but all other signals within the station area are still lit by oil lamps.
The majority of the relays used for the electrical control and interlocking are the older shelf type although more modern plug-in relays are also used for some circuits.