Radical changes to the tinplate industry began in the 1930s and continued for some twenty years. In 1930 there were 76 works producing hot dipped tinplate in South Wales, but by 1950 this number had been halved, and by 1961 they had all ceased production , though a few of the old hot dip tinplate pots continued until the last one ceased production at the Metal Box Eaglesbush, Neath Works in 1982.

Tinplate from Swansea & Llanelli
These changes were brought about by the need for greater production and lower costs, and the changing demands of improved quality by customers, accelerated by the introduction of the first continuous tinning line the Richard Thomas and Baldwins Works at Ebbw Vale in 1948.

The Steel Company of Wales was formed in 1947 and they decided to build two tinplate works in the Swansea and Llanelli districts to meet demand and soak up some of the labour made redundant at the old style works . They started clearing the site at Velindre in 1947, but work there was put on hold and the site at Trostre was developed as it was felt that the need for work was greater in the Llanelli area than north Swansea.

The Advent of British Steel
Trostre came into production in 1951 and work on the Velindre site recommenced. The Velindre works were commissioned in 1956 when each of the three works operated two modern continuous tinning lines. In 1968 the Steel Company of Wales were taken over by British Steel and with further developments each works operated with four electrolytic continuous tinning lines, producing one point two million tons of tinplate per annum.

Closure Shock
In it's heyday the Velindre works employed more than 2000 and it was considered to be the 'jewel in the crown' in British Steel, having the reputation for higher yields with fewer complaints than the other two works. Notwithstanding this and following increased worldwide competition it was decided in December 1980 that one of the three tinplate works would have to close. Bearing in mind its excellent record for quality and profit it came as a surprise to many people that Velindre would be the one to close. A total of 1,300 people were made redundant in March 1981, though 138 were found jobs at Trostre. This left just 768 on site and production was gradually run down until the works finally ceased production in 1989. Another 108 were given jobs at Trostre, and a small workforce were kept on for a short period to clear the site.

The closure of the works not only took away the jobs of the workforce, it also affected their social lives. There was a modern Clubhouse and sports field on site that were well supported by the workers, running their own football, cricket, bowls, darts, snooker etc teams. In July 2002 the Ebbw Vale works closed down and Trostre is now the only works producing tinplate in the UK .