The British Trades Union that represents musicians of all types, its members include not only performers but also composers and instrumental music teachers. Over 30,000 of them in total.

The union was founded in 1893, but has rarely intruded on the public consciousness except on the occasions when it engages in the odd bit of Luddism such as campaigning against discotheques ("keep music live") and against the Phillips music cassette ("home taping is killing music").