Ancient Monuments

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Tresilian Bay Anti-invasion Defences

A Scheduled Monument in St. Donats (Sain Dunwyd), Vale of Glamorgan (Bro Morgannwg)

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Latitude: 51.4001 / 51°24'0"N

Longitude: -3.5227 / 3°31'21"W

OS Eastings: 294169

OS Northings: 167887

OS Grid: SS941678

Mapcode National: GBR HG.R4LV

Mapcode Global: VH5J4.W2KH

Entry Name: Tresilian Bay Anti-invasion Defences

Scheduled Date: 28 October 2019

Source: Cadw

Source ID: 4379

Cadw Legacy ID: GM617

County: Vale of Glamorgan (Bro Morgannwg)

Community: St. Donats (Sain Dunwyd)

Built-Up Area: St Donat's

Traditional County: Glamorgan


The monument consists of anti-invasion defences (6 reinforced pillboxes), dating to the early period of the Second World War (AD 1940-41) that formed part of Western Command's Glamorgan coastal crust defences. They are aligned east – west, extend for 850m overlooking the gently shelving beach at Tresilian Bay to the south and are lettered A to F on the map attached to this entry. Four are of regular hexagonal design with low protected entrances located on the edge of tall limestone cliffs (A, B, C and F), whilst the other two (D and E) are of unique designs located above the high water mark at the north western and north eastern corners of Tresilian Bay. Pillboxes A, B and C are built of reinforced concrete with external red brick shuttering and D and E were carefully camouflaged with limestone blocks to match the adjacent cliff faces. Pillbox F is built of reinforced concrete with external limestone facing.

The monument is of national importance for its potential to enhance our knowledge of Second World War anti-invasion practices. It is well preserved and is an important relic of actions taken against the perceived threat of a German invasion from Ireland. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits. The importance of the monument is enhanced further by its internal group value, together with the group value it shares with adjacent anti-invasion defences to the East (Limpert Bay Anti-invasion Defences (GM601)).

The scheduled areas comprise the remains described and areas around them within which related evidence may be expected to survive:

• Areas A, B, C and F are centred on SS 94168 67887, SS 94439 67846, SS 94675 67723 and SS 94961 67660 respectively, and are circular measuring 15m in diameter. • Areas D and E are centred on SS 94750 67770 and SS 94808 67729 and are square measuring 12m N-S by 12m transversely.

Source: Cadw

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