What is the difference between bona-fide sub-contractors and labour only sub-contractors?

A bona-fide sub-contractor, also known as a ‘Supply and Fit contractor’, has current insurance in place, whereas a labour only sub-contractor does not.  Any Employers and Public Liability you take out would act as a contingency against the failure of the bona-fide sub-contractor’s policy as well as protecting the labour only sub-contractor under your auspices.