Brown-Firth Laboratories, Now English Pewter Company

Brown-Firth Laboratories, now English Pewter Company, 72 Princess Street

This is a purpose-built research laboratory and offices, now a pewter works, constructed in the early 20th century in two phases. The building is of red brick with stone dressings, slate and metal roofs featuring north light glazing and stone copings to the original block. Brick chimney stacks rise to the rear at the junction between the original block and extension, and to the extension itself.

The Princess Street elevation displays three storeys. The original section has five first-floor bays, extended by five closely matching bays to the right. The ground floor features a double-recessed doorway with rectangular overlight and stone lintel at the north-east end to the left. To the right are four round-headed, double-recessed windows with chamfered stone sills, brick voussoirs, stone keystones, and cross frames, followed by an entrance doorway with round head, stone keystone, two-panel door and semi-circular overlight. A further five similar windows continue to the right. Ventilation grilles of two patterns are positioned between the ground-floor openings.

The first floor contains ten two-light windows with chamfered stone sills and segmental brick heads. A moulded brick string course runs above the first-floor windows, with another below the second-floor windows. The second floor displays windows arranged in two groups: 5-2-5 light windows with chamfered stone sills. Windows in the original block have a continuous concrete lintel, while those to the right have individual moulded heads. Modern glazing is throughout. A cornice runs along the elevation. A rounded stair tower at the right, south-west end has a stone-capped plinth, moulded brick band, and three two-light windows, the lowest now containing plaques commemorating Harry Brearley and the invention of stainless steel.

The Blackmore Street elevation has two inserted ground-floor doorways, six rectangular windows with brick flat arches to the first floor (the two to the right being narrower), and four similar windows to the second floor.

The rear elevation features round-headed windows on the ground floor, segmental-arched windows on the first floor, flat-arched windows in the original block on the second floor, and windows matching the front elevation to the extension. Basement window openings are visible but now blocked. The rear is rendered to the left at the south-west end where it adjoins a now demolished wing, and has a 21st-century single-storey brick addition.

The interior contains cantilevered staircases with decorative metal balusters at either end of the building. The ground floor of the original block comprises two rooms deep with an exposed steel frame to the south-west. The first floor, housing offices, is divided by a central corridor with decorative mouldings to beams in the original block. Parquet floors run throughout. The second floor housed laboratories and retains benching and hearth. Copper tape has been applied to the ceiling and upper wall of many rooms. The basement contained a cinema and retains a projection room with some original fittings.

This building holds particular historical significance as the birthplace of stainless steel. It was purpose-built as research laboratories through a joint enterprise by John Brown and Firth's, two of Sheffield's largest steel manufacturers in the early 20th century. Established in 1908 with metallurgist Harry Brearley as manager, the laboratories became the site where Brearley developed a chromium steel alloy with corrosion resistance in 1913, which he named stainless steel. His successor, William Hatfield, continued research into stainless steel alloys on the site and further refined the alloy in 1924. Stainless steel has since become the best known and most widely used of all alloy steels worldwide, and this discovery revolutionised Sheffield's cutlery industry for the second time, the first being the development of crucible steel in the early 18th century, also a local innovation.