In which decade was the eleven-plus exam for English and Welsh school's established?

The eleven-plus (11-plus) is an examination administered to some students in England and Northern Ireland in their last year of primary education, which governs admission to grammar schools and other secondary schools which use academic selection. The name derives from the age group for secondary entry: 11–12 years.

Introduced in 1944, the examination was used to determine which type of school the student should attend after primary education: a grammar school, a secondary modern school, or a technical school. The base of the Tripartite System was the idea that skills were more important than financial resources in determining what kind of schooling a child should receive: different skills required different schooling.

The eleven-plus was once used throughout England and Wales, but is now only used in counties and boroughs in England that offer selective schools instead of comprehensive schools. Also known as the transfer test, it is especially associated with the Tripartite System which was in use from 1944 until it had been phased out across most of the UK by 1976.