I have done research on labour camps in the interwar period.

They were ostensibly intended to keep/make men fit for work, however they are a means of making them earn their dole, they usually attended them for about 3 months.

Life in the camps was harsh, they had to wear uniforms and their movements outside the camps were restricted. Hollesley Bay was a particulary infamous camp, where men who had committed no crime were sent, now it is an open prison were likes of Jeffrey Archer wiled away his time.

Unemployed men (read unpaid labour) were also used to build the majority, if not all, the lidos that were very fashionable then. I think the unemployed were also used to work on the Mersey Tunnel.

It is quite some time since I did this research and so cannot remember all the nuances.