Tilney St. Lawrence Patrol

The nearest known and hence most likely Patrol using this OB would have been Tilney St. Lawrence Patrol which, although it has always been situated in Norfolk, came under Auxiliary Units Lincolnshire.

The structure was built into an old flood defence bank, dating from the times when the Great River Ouse used to be much wider than it is now, from before the time the cut-off channel was built. It is made of concrete that was cast on site (with plank shuttering).

It is in excellent condition and well looked after. It has been used for the storage of Port wine for some time and all vent pipes were filled with expanding foam. Both entrance and exit openings were recently fitted with sturdy steel doors which are kept firmly locked and bolted to prevent unauthorised access.

The main chamber measures 4.30m (L) x 2.40m (W) x 2.10m (H) metres; 3 ceramic field pipe vents in roof – 6 inch diameter; 3 ceramic field pipe vents in north wall – 3 inch diameter; one vent in south wall, one in north wall – both 3 inch diameter; one 6-inch ceramic vent pipe out toilet roof. Steel pipe through roof in SW corner and emerging above ground level – 2 inch diameter, appears to have been home-made and presumably used for passing through a cable.

The main chamber is accessed through an antechamber that is about 1m wide and 2m long. A toilet cubicle measuring about 1.30m (H) x 0.80m (W) x 1m (D) has been built into its south wall.

A 1.20m deep drop separates antechamber and main chamber. At the bottom of this drop there is a cast block of concrete (9x9x18in) serving as a step.

Two round un-concreted areas, one in the floor in the south west corner of the main chamber and the other in the south west corner of the antechamber, roughly 25 cm in diameter. Excavating the soil revealed that both of these served as drains. It is orientated east west

Entrances: Drop down shaft with steel rungs in wall (2 missing/corroded) – about 2 metres deep. Entrance shaft opening rectangular – 60 x 75 centimetres; originally covered by a wooden lid with tray on top that rested on the concrete lip of the entrance opening – no trace remains of the original cover. Entrance currently secured by modern steel lid with padlock.

The emergency escape tunnel consists of two sections of concrete pipe measuring about 2 metres – emerging in north bank. No trace remains of the original trap door. The internal opening was also secured by a door of which only the wooden boards of the frame remain. This door has since been replaced by a heavy steel door bolted to the interior wall. The exit end of the pipe is encased in cast concrete with a lip surrounding the exit opening. Exit opening currently covered by corrugated sheeting.

There is a hand-operated (oil) pump, about 1.30m down from the entrance opening, on the shaft’s north wall. We established that the pump was in all likelihood used to open the cover which was described to us as having been a wooden box or tray filled with soil and planted. No trace remains of the original cover.

The vertical shaft terminates in a small antechamber from which the hand pump was operated. A section of (rusty) pipe alongside the north wall still has the original (12) coat hooks attached to it. A toilet cubicle with its own vent pipe has been integrated into the opposite wall.

A 1.20m drop leads down into the main chamber. A solid block of cast concrete is at the bottom of this drop, on the main chamber’s floor, serving as a step.

Nails can be seen sticking out of the roof of the main chamber, presumably intended to hold in place wooden battens that have since fallen off. On the interior walls of the main chamber there are wooden boards, some with nails still in them. There is evidence that the chamber contained extensive shelving.

Glazed ceramic vent pipes were set into both end walls as well as into the flat roof. A small, apparently homemade, steel pipe runs upwards through the roof. It can be seen where it emerges above ground on the south side. We were unable to establish what purpose it might have served.

The emergency escape passage is near the far end, turning off at right angles through the north wall. It consists of two sections of concrete pipe.

The exit end of the pipe is encased in cast concrete, with a lip surrounding the exit opening which is built into the slope. The opening is currently covered over with corrugated sheeting. The internal opening was secured by a heavy steel plate that was hinged at the bottom.

Both antechamber and main chamber have concrete floors. There are two round un-concreted areas, one in the floor in the south west corner of the main chamber and the other in the south west corner of the antechamber, measuring roughly 25 cm in diameter. Excavating the soil revealed that both of these served as drains.

A well-disguised exterior zinc water tank is located on the north side. The tank was originally covered with corrugated sheeting that has only recently fallen in. A water pipe was put through the wall and can be seen emerging from the interior wall. We presume that a water tap would originally have been affixed to it.

This to-date is the only OB we have seen that was constructed exclusively from concrete, cast on site. We had not as yet seen one with so many ceramic vent pipes (9 altogether) either, or one where two different sizes of vent pipes were used. We had never come across a hydraulic hand pump used for opening the entrance cover, and we had certainly never seen any evidence of shelving to the extent as can be seen here. Despite no two OBs ever being exactly the same, this one does stand out for a number of distinct features shared by none of the others we have recorded.

Other physical remains include;

Hand pump on entrance shaft wall. On occasion of a second visit we managed to establish that the pump is a hand-operated hydraulic oil pump and that it would presumably have been used for opening the wooden box covering the entrance opening.

Coat hooks on a section of pipe running along one of the walls, in the antechamber. According to the landowner, the hooks were used for hanging coats, they are original and were always there as long as he can remember.

A zinc water tank abutting north wall, measuring 1.30m x 0.60m. This tank was originally covered with corrugated sheeting that has recently fallen in. A water pipe was put through the wall and can be seen emerging from the interior wall. We presume that a water tap would originally have been attached to it.

No trace remains of the nearby ammunition store.