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The Hot and Sticky Secrets of Castle Drogo

Castle Drogo, Drewsteignton, Devon, UK


Castle Drogo is a large stately home on the eastern side of Dartmoor. Constructed between between 1911 to 1930 by architect Edwin Lutyens for English enterpreneur Julius Drewe in the image of a medieval castle featuring a good twist of Lutyen's design genius.

Julius Drewe was a true British Empire success story, born in 1856 aged 18, he started working as a tea buyer in China.

He opened his first tea shop in Liverpool in 1878, from 1883 in London he grew his business rapidly giving it the name of Home and Colonial Stores. It took just six years, for him and partner, John Musker, to retire from the business as wealthy men. Drewe was 32.

In 1919 they sold their shares in Home & Colonial for £3.5 million, a huge sum at the time.

From his retirement Drew was able to enjoy his wealth, with his wife, he travelled extensively but his life project was the creation of Castle Drogo


The site is 450 acres and although the building is made of Dartmoor granite, the ground it stands on is a metamorphised carboniferous rock promontory overlooking the Teign Gorge.

The castle build is vast and its walls thick with reinforced concrete faced with dressed granite blocks, with fine carved details to windows and battlements etc.

The granite for the western half of the castle was quarried locallly at Blackingstone Quarry, Moretonhamstead. Devon.

The granite for the eastern half came from further afield, quarried at Merrivale Quarry, near Tavistock, Devon.

Merrivale is known to mineral collectors for its "hot" minerals, in particular autunite and phurcalite.

Both minerals are found typically as yellow microcrystals formed on fracture surfaces of the granite host rock.

During my visit I didn't see any yellow patches on the walls, but it would be interesting to find out what the background radiation levels are within Castle Drago!

Autunite from Merrivale Quarry, Tavistock, Devon, UK (FOV: 20mm) Merrivale Quarry, Whitchurch, Tavistock, Devon, UK


The other intriguing mineralogical secret to Castle Drogo is also its Achilles heel, much documented and the cause of a multi-million pound rescue/refurbishment programme by the owners, the National Trust.

By all accounts during the construction there were some disagreements between Drewe and Lutyens over overall design. Lutyens wanted to create pitched rooves above the battlements. 

Drewe wanted a flat roof befitting his medieval vision, and also to provide rooftop terraces, to take advantage of the elevation and the panoramic views.

Of course Drewe had his way and the roof was constructed of flat concrete sealed with asphalt (bitumen) covered with granite setts or flagstones.

Several tons of natural asphalt were sourced from the West Indies, specifically from Pitch Lake, in Trinidad.

Sir Walter Raleigh first came across Pitch Lake in 1595, however already known by the Spanish name Tierra de Brea.

Raleigh was first shown the 100 acre black "tar" lake by Amerindian guides, straight away he saw the value of the raw material for waterproofing ships.

Mining at La Brea began 1867 with around 10 million tons of asphalt recovered since. Primarliy used for road surfaces, locally and on the other islands of the Caribbean, and exported globally.

Reserves at La Brea are estimated still to be around 6 million tons, and extraction continues.

Postage Stamp Commerating Raleigh & Tar Lake  Asphalt - Tar Lake, La Brea, Siparia, Trinidad


Once completed the roof has leaked almost from day 1. The uneven expansion and contraction of the materials, and the properties of the ashpalt in the Dartmoor climate meant it quickly lost its elastic and waterproof properties and failed.

Currently the 5 year restoration project on Castle Drogo is nearing completion, this is expected in by the end of 2018.

Castle Drogo Roof Restoration should complete in 2018  - (courtesy National Trust SW)


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