South Sutor, Mine Watching Observation Post

A bunker with an observation post. The entrance to this building is from the S side down a short stair. A short passage leading to the stairs up to the observation post has a doorway on the W side.

The observation post was used for watching for planes dropping mines at the entrance of the Cromarty Firth, plotting their position and reporting for mine clearing. It also played a part in the controlled minefield. The bunker part, entered from the doorway in the short passageway was part of the detection systems employed at the Sutors. Laid along the sea floor across between the Sutors, were the indicator loops which picked up magnetic changes when a metal ship/submarine passed over the loops. These were picked by a machine called a galvanometer which detected the slight changes in the electric current. Up to six galvanometers were in use. The room contains cables ducts in the floor and further cable ducts with electrical cables still in situ can located in three of the four corners of the single room.

Information from RCAHMS (AKK) 25 July 2013.

This Mine Watcher’s Station, which is situated in semi-improved pasture 8.5m N of the Fire Command Post (NH 86NW 11.1), formed part of the infrastructure of the battery introduced by the Army in the Second World War. It is encased in an overgrown earthen blast wall, measuring 1.6m in height and about 14m from WSW to ENE by 11m overall. A pipe crowned by a cylindrical cast iron ventilation cowl projects through the turf close to the NE corner of the mound. The building comprises two compartments linked by a passage and steps: an underground block that contained the sensitive galvanometers and an observation post projects E from the NE corner of the latter, but at a higher level. A flight of concrete steps at the SE corner of the building leads down to an original wooden door providing access to a very short passage. There is an entrance immediately to the W leading into the underground compartment that contained the galvanometers, while another shorter flight of steps at the passage’s N end leads up to the observation post. The galvanometer compartment is rectangular on plan and measures 5.6m from E to W by 5.2m transversely within reinforced cast concrete walls 0.38m in thickness and 2.53m in height. Asbestos panels attached to wooden batons cover the black painted ceiling and, although now removed, also once clad the walls. The arrangement of the cable ducts and the sets of bolts in the concrete floor, in addition to the pair of concrete stands on the W side of the room, suggest two sets of machinery were originally housed here.

The observation post at the top of the N flight of steps projects E, while its three narrow, wood-framed windows provided outlooks to the N, E and S. Its walls and ceilings have also been lined with asbestos panels, although the cement walls have not been blackwashed as they have been elsewhere in the battery. A broad circular aperture on the N side of the ceiling links to the ventilator on the top of the mound, while a smaller one is situated closer to the W. Ducts for cables pass through the W into the galvanometer compartment.

The building is annotated ‘M. W. S.’ (Mine Watchers’ Station) on a plan of the battery in the Fort Record Book held in the National Archives at Kew (WO78/5192). It is also visible on an RAF aerial photograph (Scot-106G-RAF-0751-6036) flown on 31 August 1945 and on an oblique from the E (USN 218 206-0097) that was also flown in 1945.

Visited by HES, Survey and Recording (ATW, AKK), 19 February 2020.