HORSA is the acronym for the 'Hutting Operation for the Raising of the School-Leaving Age', a programme of hut-building in schools introduced by the UK Government to support the expansion of education under the Education Act 1944 to raise the compulsory education age by a year to age 15.
Government plans to increase the school leaving age resulted in the need to accommodate 168,000 additional pupils. Along with the need to replace buildings lost and damaged in World War II and the post-war baby boom, this contributed to massive demand for low cost prefabricated 'hut'-style classrooms and other school buildings. 7,000 new classrooms and 928 new primary schools were built in 1945-50.
The programme was the responsibility of George Tomlinson, the Minister of Education in the post-war Clement Attlee government. There is some evidence the programme struggled to cope with demand. However, the scheme progressed and was regarded as complete by 1950.