Ok, I said I wasn't going to do the referendum, but there's nothing else to talk about and I think this is worth mentioning.
Way back in the mists of time when I was starting out in the workplace, it was commonplace for new employees, especially junior researchers and academics, to be employed on the basis of short contracts. Open ended positions still existed however, and different institutes had different attitudes towards moving contract staff to open-ended positions. My first employer did it by creating an entirely new open-ended position, which was widely advertised. This was of course pretty stressful for the internal candidate having to fight for “their” job, although in practice it was just a huge waste of time for the external candidates who were never really in with a shout for a job which was designed for someone else. Not to mention being pretty awkward for staff like me having to talk to and show around these candidates without letting on that the job was really meant for the guy in the adjacent office who happened to be away that day. My next employer had more of an internal review process, similar to but far less formal than the US university tenure review system. My internal review was the day after I'd just got my job offer from Japan, which made it more fun than it might otherwise have been :-)
Incidentally, “permanent” is not a great term to use for these positions. No jobs are permanent in the UK, it is not uncommon to make people (or to be precise, their positions) redundant, as the chemistry department at Exeter Uni learnt to their cost. But making positions redundant costs money and takes time: much easier, management thought, to just allow contracts to end efficiently and painlessly (for them). This was also in line with the long term trend for research councils to be more "responsive", ie quicker to follow new fashions and not be tied down with things like staff or institutes or facilities to support, or long-term strategies to think about and follow through on. But I digress.
Some people were stuck indefinitely on a succession of short contracts, with no guarantee of renewal. I think one of the Reading people who visited us in Japan had been on 1-year contracts for something like a decade. Of course, a succession of short contracts, even if there's some sort of likelihood of renewal, are no basis for buying a house, raising a family, or even building a career.
Along came the interfering bureaucratic EU, who observed that this was not really a fair or sustainable state of affairs. And at a stroke, in the admirably brief and readable Council Directive 1999/70/EC, they put an end to it. Short contracts are still allowed for a finite duration, or where they can be objectively justified. But the directive underlines that the normal form of employment contract is one of indefinite duration. In practice, the research institutes and universities have pretty much abandoned short contracts, employees may get one on initial employment or for a particular project, but this no longer carries on indefinitely.
Incidentally, Japan is still struggling with this issue two decades later, in its own inimitable manner. Around the time we left, a law was coming in to limit contract employment to 5 years of continuous work, following which it would be regarded as open-ended. Prior to this new law, there was some sort of established precedent that after 9 years in the same job, you could claim open-ended status, but JAMSTEC had been careful to set up enough loopholes in our employment that there's no way jules and I were going to trust the legal system to actually enforce this in our favour. JAMSTEC's initial response to this new law was to state that all future contract employment would be on the basis of 5 years work and then a 6 month “break” (ie unemployment) followed by another 5 years work etc. I'm pleased to say that when my manager explained this to me, I laughed in his face and told him that he, and the institute directors, were all idiots if they thought that was going to work. Eventually they came up with a saner tenure review plan but excluded us from it, as I have probably mentioned here before.
So, the tl;dr version is that at a stroke, the EU abolished an unsustainable, abusive and unfair system of short-term employment, and this move has also had the benefit of making management think a little more carefully about the long-term sustainability of their institutes. The widespread RCUK fellowships (5 years of research which converts to an open-ended lecturer position) were one obvious response to the change in the law. Younger scientists probably don't even realise this, as the short contract era will have ended before they started work. But it has certainly made a big difference to scientific careers in the UK, and no UK govt had shown any inclination to do anything about it.