Now it would be interesting to see the opinion of the court on fake IT contractors (SSII), where as a developer you are a full-time employee of company X, rented for years as full-time "consultant" to company Y, on premises of company Y, just with lower salary and no profit sharing & no bonuses that staff of company Y enjoys. (This has been a common practice of Microsoft in US in 1990s and they lost a lawsuit on that…
I've been (remotely) involved in such a mass (about a dozen FTE) requalification 10 years ago. Needless to say, the rules for contract duration and conditions were strongly tightened up afterwards.