The story
Hyder PLC was created in 1996 following the takeover by Welsh Water of the electricity company SWALEC for £872m. By 1998 it was Wales' largest independent private employer, and had quadrupled its turnover since SWALEC was privatised in 1990. (since 1996?).
Hyder owned Swalec and Swalec Gas brands and combined international, leisure, infrastructure and construction interests. Other subsidiary companies/brands of Hyder included Transis (operator of fleet vehicles), Laing Hyder (construction consortium), Hyder Investments, Celtic Infrastructure and Lusis (IT provider), several hotels in Wales, a small stake in cable company NTL and a 36% stake in Severoceske Vodovody a Kanalizace, the Czech water company.
However, the debt taken on to finance the takeover of Swalec left the company vulnerable to external shocks. In these circumstances, the 1998 windfall profits tax on the utilities introduced by the new Labour government, combined with the price cuts required by the 1999 Ofwat price review made Hyder's share price plummet (from a peak of 1048p in January 1998, to a low of 179p in March 2000).
From Wikipedia’s article on Hyder (defunct company), shared under CC BY-SA 4.0.4