You are here:
History Trail /
Mills Bakery

Mills Bakery

The engine room of Royal Navy rations.

Step inside the grand Mills Bakery and imagine the relentless rhythm of an industrial marvel: steam engines churning, millstones grinding, and ovens roaring. In just one week, this powerhouse could transform 1,000 massive sacks of flour – more than 270,000 pounds – into ship’s biscuits, the rock-hard ration that fuelled sailors on epic journey around the world.

At the heart of Royal William Yard’s ambitious vision, architect Sir John Rennie’s bold innovation placed both flour mills and bakeries under one roof for the first time in naval victualling history, revolutionising the speed and efficiency with which the fleet’s food was produced.

Bread and biscuit making:

an industrial spectacle

Arrival and storage: grain was hoisted to the upper floors, where it was cleaned, ground into flour by powerful steam-driven millstones, and moved down through the building via chutes for baking.

Milling power: Two 40-horsepower steam engines drove as many as 27 sets of millstones (some sources note up to 34), grinding up to 1,000 bushels of ‘corn’ (wheat) every hour – an output unrivalled in its day.

Biscuit production:

The flour was fed into vast industrial mixers with salt and water to make the biscuit dough
Dough was kneaded, then rolled out, by mechanical rollers
Sturdy cutters – also steam-powered – pressed the dough into into perfectly uniform ‘ship’s biscuits’
Once cut, the biscuits were conveyed into one of 12 enormous ovens, where they were baked until rock hard (’hard tack’), then sent for drying and storage
Each naval bakery had its own biscuit stamp – here at the Yard biscuits were stamped with the government arrow and a ‘W’ for William

Alongside biscuits, the industrial kitchen also produced soft bread and, according to some sources, even milled chocolate – testament to the extraordinary scale and adaptability of the Yard’s operations.

Through fire and flour:

the Bakery’s blazes

For all its innovation, Mills Bakery faced frequent danger. Over its working life, the building survived several major fires, sparked by the immense heat of its furnaces and the ever-present flour dust. The most dramatic blazes include:

1929 fire: Damaged elements of the bakery and caused major stock losses, despite the best efforts of local fire brigades.
1960 inferno: Another major fire occured, specifically in the East Loft Bakery block. This massive fire raged for hours, going on to destroy large stores of clothing and gear; firefighting teams from across Plymouth, naval barracks, and four tugs converged to battle the blaze. Locals recall watching the drama unfold and even scavenging waterlogged items – including legendary ‘sea boots’ – on nearby beaches.

While the most well-known fires at Royal William Yard affected the Mills Bakery, a clothing store blaze in 1920 stands out in the site’s history for the scale of its destruction. The estimated value of items lost in the fire was substantial, calculated at £210,609 at the time – a considerable loss for the Yard and the Royal Navy.

Did you know?

The Makaton sign for biscuit – tapping your elbow – mimics the real-life motion of sailors cracking open biscuits in the crook of their arms to shake out the weevils. It’s a piece of living history born right here in buildings like this.