Defence against potential invasion by German forces after the withdrawal from Dunkirk became the main concern of the early years of the Second World War. The first level of ground defence was based on forming a "coastal crust" to resist the initial invasion (If you are interested, several other caches in the East Lothian at War series deal with elements of the coastal crust in the area.)
Inland, fixed defences were put in place to resist the advance of any enemy force that got ashore. In some areas these were arranged along natural obstacles such as rivers or canals and set up as “Stop Lines” to slow and hold advancing forces. McKryton has set up a series of caches in Fife to mark elements of the Fife Stop Line which gives an excellent picture of how these defences would be managed. A Bookmark list is here. East Lothian had no designated Stop Line. Instead the interior lines of defence concentrated principally on positions which could cover roads and other transport routes and so impede any enemy advance.
This cache is at the site of a weapons emplacement for a Spigot Mortar to be manned by members of the Home Guard and which would have covered what was then the main A1 route up Pencraig Brae. Despite the infill of rubble and the trees now growing here, you can see the outline of the weapons pit and the top part of the concrete pillar with the stainless steel pin which formed the firing position for the mortar. If you imagine away the hedge in front of the position you can also visualise the effective line of fire at any vehicles coming up the brae.
The Spigot Mortar, or "Blacker Bombard", was invented by a Lieutenant-Colonel Blacker with the aim of providing cheap and easily produced weapons after most of the British Army's heavy equipment had been lost at Dunkirk. Other field weapons invented for the same purpose during this period were the Northover Projector and the Smith Gun.
The Blacker device fired a 20lb fin-stabilised high explosive mortar bomb propelled by black powder, and had an effective range of 100yds in its anti-tank role and up to 450yds when firing a lighter anti-personnel bomb. Not only did it have a short range, it had another major drawback - when the warhead hit its target, the fins would often fly backwards endangering the firing crew.
In a fixed position like this, the mortar was mounted on a steel pin set into a substantial base of reinforced concrete. This was in turn set within a camouflaged weapons pit to offer some protection to the three man gun crew.
A portable mount was also available, but weighed around 350lb and took 3 men to move it.
The spigot mortar was rejected by the regular army but many were produced for use by Home Guard and airfield protection units from 1941-1944.
Getting There
Park at the Pencraig Hill Picnic Area off the A199. The cache co-ordinates will take you there. From the end of the parking area a small path leads eastwards. The weapon pit is built against the wall to your left as you walk along the path.