It's actually the contractor who loses dispensations if they have the same gig for > 2 years. As it is still technically a B2B contract the timescale is not an issue. We have 100s of contractors over 2 years and no rights accrue.
Everything else Saint Keith says is spot on, don't confuse 'temp' work with 'contract' work.
Actually one of the few things on the board I am qualified to have an opinion on!