Building record MDO47638 - Signal box, Hamworthy Station, Poole

A signal box standing towards the northern end of the central station platform at Hamworthy Junction, and is orientated north-south. It was erected in 1893, when the station was completely rebuilt. It is of a standard type 3C design for the LSWR and is rectangular on plan. It is constructed of brick to the ground floor, with a timber-framed and weatherboarded upper storey. It has a hipped, slate roof and originally had a wooden roof ventilator which was removed in the mid-20th century. The building is of two storeys, with a locking room to the ground floor and an operating room above. The square-headed small windows to the ground floor (boarded over) are set within recessed panels of brickwork. The fenestration to the operating room originally comprised sliding sash casemented windows with timber glazing bars; these were replaced with much smaller windows in the second half of the 20th century. There is a modern station name plate on the eastern side. At the southern end of the structure, a flight of wooden steps leads from platform level up to a timber lean-to porch, from which the door to the operating floor is accessed.

Signal boxes arose from developments in signalling, appearing in the 1850s, in particular in interlocking signalling systems. A notable pioneer in the development of interlocking signals was the railway contractor, John Saxby who patented such a system, termed `Simultaneous Motion¿, in 1856. Important subsequent developments included the invention of the lever-and-tappet locking system, from a patent of 1870 by the firm of Stevens & Sons, which became a standard national type. The requirement to shelter and house the operating equipment (and the signallers) led to the introduction of the signal box as a common railway building. Signal boxes became a standard type of railway building from the 1860s onwards, with a basic design established by the 1870s that was to alter little in essentials until after World War I. From the 1870s onwards was also a tendency to design signal boxes with greater architectural finish, adding features such as gabling, or roof finials (although they always remained relatively cheaply built).

Hamworthy Junction is located on the Southampton and Dorchester Railway, from 1848 the London and South Western Railway (LSWR), which received Parliamentary Assent in 1845 and opened in 1847. The station at Hamworthy was originally called Poole Junction and opened in June 1847. It was renamed Hamworthy Junction in 1872, and finally Hamworthy in May 1972. The branch line from Hamworthy Junction to Lower Hamworthy served Poole until the development of a railway line into the town itself. The Hamworthy line closed to passenger traffic in 1896; but continues to carry freight traffic. Hamworthy Junction signal box was erected in 1893 when the station was completely rebuilt. The LSWR never adhered rigidly to standard drawings of signal boxes, and produced many variants of the 'standard' structures. The signal box at Hamworthy Junction is a type 3C. Documentary evidence indicates that it originally contained a frame of 56 levers, manufactured by Stevens and Son, to which three further levers were added in 1901.

Hamworthy Junction signal box stands towards the northern end of the central station platform and is orientated north-south. It is of a standard type 3C design for the LSWR and is rectangular on plan. It is constructed of brick to the ground floor, with a timber-framed and weatherboarded upper storey. It has a hipped, slate roof and originally had a wooden roof ventilator which was removed in the mid-20th century. The building is of two storeys, with a locking room to the ground floor and an operating room above. The square-headed small windows to the ground floor (boarded over) are set within recessed panels of brickwork. The fenestration to the operating room originally comprised sliding sash casemented windows with timber glazing bars; these were replaced with much smaller windows in the second half of the 20th century. There is a modern station name plate on the eastern side. At the southern end of the structure, a flight of wooden steps leads from platform level up to a timber lean-to porch, from which the door to the operating floor is accessed. The interior of the upper storey operating floor is dominated by the 59-lever frame. Above the lever frame at chest height there is a wooden narrow board, on which is mounted various sorts of signalling display equipment.

At the northern end of the platform at Hamworthy Junction is a post-mounted semaphore signal. It has a quadrant signal, where the arm is lowered from a horizontal to an inclined position.

Transport buildings and structures of all types form key elements in our historic environment and those dating from before 1840 will be serious contenders for designation. After 1840, however, greater selectivity is required as survivals are more common and designs increasingly
standardised. Signal boxes have declined in numbers from 10,000 to some 700 and designation has attempted to protect a representative sample of the principal types and preference is given to examples that have minimum impact on rail safety (e.g., those on preserved sites or lines).

As set out in the English Heritage Selection Guide (2007) for Transport Buildings to merit designation, signal boxes should either represent a relatively early phase of architectural design or technological development, or should demonstrate some significant later technological novelty and innovation, or new architectural design. Hamworthy Junction signal box is of a fairly conventional design and is not innovatory for this period of railway history. Type 3C signal boxes, such as this example, were erected on the LSWR between 1890 and 1897. Standard features included hipped roofs, horizontal boarding, a lean-to porch, and a roof ventilator. The type 3C also lacked the decorative details found on many other late-19th century signal boxes elsewhere on the rail network. While Hamworthy Junction signal box retains its hipped roof and is a typically plain structure, it has crucially lost its original operating room windows and its wooden roof ventilator. Much of the architectural interest of signal boxes lies in their fenestration and the loss of the original timber glazing detracts significantly from the interest of this signal box. This is clear from the comparison of recent photographs with archive images from 1952 and 1968.

Nonetheless, the survival of the lever frame, which was extended in 1901, and other traditional signalling equipment is relatively substantial. Indeed, not all listed signal boxes have such survival of internal equipment. However, there are good examples of listed signal boxes which survive with a substantial part of their original equipment intact, including Exeter which is a LSWR modified Type 1 design of 1870. Additionally, while Hamworthy's lever frame is notable for its impressive size, there are a small number of comparably large, or even larger, examples preserved in the list: most notably the London and North Western Railway signal box at Severn Junction, Shrewsbury of 1903, which has a frame of 180 levers.

In summary, Hamworthy Junction signal box is not recommended for listing: it is not sufficiently early to be notable as a mechanical signal box, it is unremarkable architecturally and technologically, and does not represent an important phase in the development of signal boxes and signalling technology. Its internal equipment, whilst a notable survival is, however, fairly typical both technologically and in its appearance, and does not qualify in its own right for designation. Nor does the signal box benefit from any group value with other listed buildings.

The semaphore signal at Hamworthy is described as the only remaining example of this type on the South Western Main Line. Semaphore signals were patented in the early 1840s by Joseph James Stevens, and soon became the most widely-used form of mechanical signal, although they are now decreasing in number. Historic photographs show that the Hamworthy signal was originally mounted on a lattice post and had a parachute finial which has been removed. Much of its historic fabric has thus been replaced or lost, and it does not, therefore, warrant statutory designation. (1)

<1> English Heritage, English Heritage Listing File, Adviser's report on case 169498, in file 507886/001 (Scheduling record). SDO17502.

<2> National Record of the Historic Environment, 1517614 (Digital archive). SDO14739.

Record last edited

Dec 30 2023 8:52AM