This letter was sent to Elizabeth M. Watkin Jones, Secretary of 'Pwyllgor Amddiffyn Capel Celyn' (the Capel Celyn Defence Committee), by the National Union of Mineworkers (South Wales Area), 14 February 1957. The Defence Committee was formed in March 1956, shortly after it had been announced that Liverpool Corporation was intending to build a new reservoir in the Tryweryn valley, drowning the village of Capel Celyn, north of Bala.

The Committee launched a spirited campaign to oppose the proposal to drown Cwm Celyn. In addition to canvassing support from local authorities, individuals and national institutions, the Committee organised a series of protest meetings, conferences and rallies across north Wales and in the city of Liverpool. This letter is one of hundreds of letters of support sent to the Committee by various organisations across Wales.

Ultimately, however, the efforts of the Committee to halt the building of the new reservoir failed and on 1 August 1957 the Liverpool Corporation Act was passed. Work began on the site three years later and was completed in August 1965.