Re: "between 2007 and December 2014"
You can easily be a fixed term employee and get rolling contracts, or even just employ and then make redundant when the project finishes and they can't be moved to another project, like evry other employee?
It's not as though onboarding an employee is difficult or onerous, the issue is just that there would have to be a massive wage drop for the 'contractor' or a massive rise for the other employees. That's where it becomes difficult. You can justify the higher contractor rate be 'contractor, innit'.