Boulby sound mirror

The grade II listed sound mirror at Boulby on the Yorkshire coast was built in 1916, during the First World War. According to the Historic England monument record, this sound mirror was used “specifically to provide early warning of Zeppelin attacks on the Skinningrove Iron Works 5km to the north west.” Skinningrove works manufactured high explosives and later mustard gas.

These pictures were taken on 29 December 2002 (with permission from the owner of the site).

[Picture of the Boulby sound mirror from the front]

The Boulby acoustic mirror is on top of a hill, facing north-northeast towards the sea. It is of the same design as the one at Redcar, but different to the Kilnsea one.

According to the scheduled monument record, this mirror “is the only one where the location and earthwork remains of the listening trench survive and important evidence of how the mirror operated in the field will be preserved.”

[Picture of me stood in the dish]

To give some idea of the size of the mirror, I’m about six foot tall.

[Rear view of the Boulby sound mirror]
The mirror is adjacent to the road in a field on top of a hill. The rear of the mirror can easily been seen from the road.

Two other sound mirrors covered the Tees estuary, one at Redcar and one at Hartlepool (now demolished).


View Sound mirrors in a larger map

The mirror is west of Boulby Barns Cottage on Boulby Bank. Map. It is in a field between two farms, and is on land belonging to the westernmost. The rear of the mirror is clearly visible from the adjacent minor road.


  • Historic England record.
  • Tees Archaeology has an aerial photo of the mirror (it’s at the near end of the darker green field to the right-hand side). They say: It was probably constructed in 1916. The structure is made from reinforced concrete set with corrugated iron shuttering. The sound mirror is a squared U shape in plan and is 17ft high. It survives in good condition although there is some decay to the concrete.


News about the Boulby sound mirror.

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