The British Federation of Co-operative Youth was a organisation for persons aged 15-24. It's long been defunct. Back in the 1940's and early 1950's there was a branch at Hardy Lane. There were at least two others in south Manchester at Didsbury and Wythenshawe. A notable local co-operator Walter Frost - later a Labour Councillor, and a Director of M&S Co-op started his co-operative career as a leader of these organisations.
It was never a major British youth movement with a large membership. It's timeline looks briefly like this :
1922 various local co-operative youth groups in existence across Britain were termed 'Comrades' Circles'. There was such a group at Barlow Moor around 1934.
1924 - the British Federation of Co-operative Youth (BFCY) was founded by young members as a national body with the purpose of organising and co-ordinating Circle activity.
1937 - Membership figures are available. Comrades' Circles possessed 8,000 members. Britain's largest youth organisations, the Boy Scouts had 448,396, the Girl Guides 581,000, and the Boys' Brigade 111,442, the Woodcraft Folk had 5,000.
1941 British Federation of Young Co-operators (BFYC) formed when the BFCY was wound up by the Co-operative Union.
Further reading :
Pleasure, Politics and Co-operative Youth: the interwar Co-operative Comrades' Circles
by Selina Todd in Journal of Co-operative Studies, September 1999, No.32.2