the builders union was blown out in the 1970s after the builders strike. they needed to be on strike for 12 months before anyone would notice.
some building sites were union only, how anyone could live on their rates of pay , tool money , traveling time , bonus that you shared 50/50 with the com.
i was on the lump, a lump price to plaster a property, no sick pay, holiday pay just paid out in cash every week about double the wage of a union man. i drove a jag, the union man was on a bike or the bus !
They didn't ask if you wanted to join they told you you had too...in no uncertain terms.