Robertsbridge Furnace

Overview

A charcoal-fired Wealden blast furnace and its paired finery forge, built from 1539 on the dissolved Robertsbridge Abbey estate by Sir William Sidney. Worked intermittently until 1793, it produced pig iron, wrought iron, steel and cast ordnance, and is one of the best-documented Wealden ironworks thanks to the surviving Sidney family account books. Both furnace and forge pond sites survive only as dry earthworks.

History

Sir William Sidney purchased the dissolved Robertsbridge Abbey estate in 1539 and engaged the ironmasters Alexander and John Collins to build a forge and blast furnace; the furnace was completed in 1541 and began supplying pig iron ('sows') to the forge that summer, but its pond bay breached in flooding the following year and had to be rebuilt. The furnace then stood idle for 27 years from 1546, reportedly owing to the high sulphur content of the local ore, while the forge continued working on iron supplied from Panningridge and other Wealden furnaces. The estate passed to Sir Henry Sidney in 1553, and in 1565 two steelworks were established, one at Robertsbridge Abbey itself and another at nearby Boxhurst Farm, processing imported iron plate from Glamorgan — but steelmaking here ceased to be profitable by 1572 against cheaper Baltic imports, and the furnace came back into blast the following year. A 1609 record under John Hawes describes buildings lying between two fresh-water rivers, abutting 'the great stone bridge at the Forge Pond,' and including eight steel forges. Sir Thomas Webster purchased the estate from the Sidney family in 1725, and detailed expenditure accounts from 1726-35 — part of the wider documentary record that makes Robertsbridge one of the best-studied Wealden ironworks — record gun-founding activity from 1728 onward, the furnace by then casting cannon and cannon balls. Lessee John Churchill reported his furnace had 'blown up' in 1764, was declared bankrupt in 1767 and died soon after; the lease of forge and furnace passed the following year to James Bourne, William Polhill and David Guy. The furnace closed permanently in 1793, part of the general collapse of the charcoal-fired Wealden iron industry against coke- and coal-fired competition elsewhere in Britain; the forge no longer appears in the accounts after that date, and the site was put up for sale in 1801 following the bankruptcy of forgeman Thomas Willis. Pig iron for the works also arrived overland: 'Sow Lane,' a packhorse and ox-cart route climbing from Ashburnham Furnace some ten miles away via Penhurst Lane and Mountfield toward Netherfield, is recorded as having carried pig iron by ox-team from Ashburnham toward Robertsbridge — making Robertsbridge both a producer in its own right and a receiving point on this inland route, distinct from its own outbound shipments of finished ordnance, which went by land to Maidstone or by barge down the River Rother from Udiam Bridge to the port of Rye.

Workings

The furnace and forge functioned administratively as one unit despite having separate ponds some 400-500 yards apart. An unusual leat or dyke roughly 300 yards long, cut through high ground, delivered water east to the forge site, where a large water wheel on the cam-shaft drove the hammer and smaller wheels along the same channel drove the bellows. The works produced pig and wrought iron from ore smelting and fining, steel (using imported Glamorgan plate iron via eight recorded steel forges in 1609, though unprofitable after 1572), and cast ordnance — cannon and cannon balls of 7½ and 9 inch diameter. Average recorded forge output was around 40 tons a year.

What remains

Both furnace and forge sites survive only as earthworks. At the furnace site (OS grid TQ 751 231) the pond bay survives with the pond now dry, and 'First' and 'Second Ponds' are visible as field earthworks; at the forge/Abbey site (TQ 756 236) no pond bay survives but the 'Lower Ponds' remain visible along with traces of a former leat and hammer dyke. No structures survive above ground at either site.

Abandoned workings can be dangerous — unstable ground, uncapped shafts, flooding and bad air are common even where a site looks safe from the surface. This entry describes history and general location only; it is not an access guide.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• The furnace, built from 1539 by Sir William Sidney, was completed in 1541 but stood idle for 27 years from 1546, reportedly owing to the high sulphur content of the local ore, coming back into blast in 1573. ¹
• Two steelworks were established in 1565, at Robertsbridge Abbey itself and at nearby Boxhurst Farm, processing imported Glamorgan iron plate, but steelmaking ceased to be profitable here by 1572 against cheaper Baltic imports. ¹
• The furnace closed permanently in 1793; the forge no longer appears in the accounts after that date, and the site was put up for sale in 1801 following the bankruptcy of forgeman Thomas Willis. ¹
• Finished ordnance from Robertsbridge was shipped by land to Maidstone or by barge down the River Rother from Udiam Bridge to the port of Rye. ²
• Both furnace (TQ 751 231) and forge/Abbey (TQ 756 236) sites survive only as dry pond-bay earthworks, with no structures surviving above ground at either. ³

Sources

1. (secondary) Robertsbridge — Time line — Wealden Iron Research Group
2. (primary) The Historical Geography of the Wealden Iron Industry — Ernest Straker, 1931 (Internet Archive)
3. (secondary) Wealden Furnaces and Forges (East Sussex, article 6) — Geograph Britain and Ireland

Record created: 26 August 2026 · Last researched: 26 August 2026