Factory-map coverage is 1981–2024, as a documented subset rather than an exhaustive census. The 1981–1989 extension uses plant-specific historical evidence, including former works absent from the 1990 roster. National workbook totals are not evidence for individual factory operation. Llanwern steelmaking is included through 2001 and excluded from 2002; later rolling is not steelmaking. Named unresolved histories remain below. Map: only documented primary EAF or integrated BF–BOF steelmaking works, consolidated across components/owner aliases. An interval is included if it overlaps any part of the selected calendar year. Closure and restart years are retained at the precision of the evidence; short outages are not comprehensively reconstructed. This is a documented route-history reconstruction, not an exhaustive census or proof of year-round operation. No point-workbook emissions, pollutant records or source-ID counts enter the UI or national model. The NAEI point workbook is used privately only to cross-check works identity and locations from 2005; independent operator, Parliamentary, regulator and heritage sources establish routes and operating intervals. Pre-2005 historical works are reconstructed from those sources. Some historical locations are approximate; see individual evidence notes. Planned EAFs and rolling-only, research, admin, foundry-only and remelting-only sites are excluded. Forgemasters is included because primary EAF liquid-steel/ingot production is documented.
Boundaries: Natural Earth 1:50m. Map rendering: D3, licence. Point coordinates are converted from British National Grid using OSTN15 where available. The map covers the UK; no eligible Northern Ireland steelmaking works was established in the reviewed evidence.
