There can be no compromise on free movement of workers. The UK can't expect to have its cake and eat it. There can be no "cherry-picking" of the advantages of the single market. The mantra from German Chancellor Angela Merkel and most of the leaders of the EU ever since the UK voted to leave the Union three months ago has been unrelenting. If the UK wants to trade freely with the rest of the continent, it must allow people to move freely as well.
Don't expect that line to last. Why? Because Germany is about to face the same pressures that led the UK to vote to leave. Germany is starting to see precisely the same kind of trends as Britain has seen, with high levels of job creation, and yet with those positions nearly all filled by cheap migrant workers – and the knock-on effects that has on productivity, pay and social cohesion.
When the EU had only nine members, all at roughly the same level of economic development, free movement of labour was a great idea. A few architects or engineers might travel from the UK to Germany, or France to Italy, but it was a right which only a small number of people exercised. Few blue-collar workers bothered.
The difference in wages was not even close to being enough to justify the upheaval involved. In fact, not many professionals bothered either. Language barriers made it too hard for most to move, and differences in qualifications often made it impossible. It worked fine, precisely because so few people actually worked in other countries.
Extending the EU to eastern Europe changed all that. Suddenly there was a mass movement of workers, first to Britain, and then more slowly as interim restrictions were lifted, to other European countries as well. For the Poles, the Czechs and the Hungarians, wages were ten times more in western Europe than anything they could earn at home.
For the Romanians and Bulgarians it was more like 20. We have few clear empirical experiments in economics, but this one was clear: offer people ten times as much money, and they will move country. We saw that most dramatically in the UK, with more than a million east Europeans coming here, transforming the labour market.
The same thing is now happening in Germany. Last year, the country created 403,000 jobs, according to High Frequency Economics. But unemployment only fell by 113,000. The difference? Immigration, mainly from eastern Europe, as well as from the one million refugees who have flooded into the country in the past year. As new jobs are created, they are filled by newly arrived workers from abroad, not by unemployed Germans.
According to the central statistical agency in Warsaw, there are now 2.6 million Poles overseas, or 6% of the country's population. Hardly surprisingly, the largest number are in the UK, home to 720,000. But there are now 655,000 in Germany, and that number is rising faster than it is in Britain. As you might expect, they go where the jobs are – there are fewer than 100,000 in depressed Italy, for example, even though it is a similar size to the UK.
Germans are not likely to feel any more comfortable with this than the British have been. That will then be reflected in the politics. Right now, most of the EU insists free movement has to remain part of any trade deal with Britain. But that will change when other countries start to feel the same pressures that Britain is feeling as the economy gets hooked on cheap labour. We may not be able to get access to the single market and control of immigration now. But in a few years the rest of Europe will he happy to give it to us – because they will want it too.
The UK's 10 best-paid jobs
The UK's 10 best-paid jobs
Flying high literally as well as metaphorically, pilots top the salary scale this year. There are various routes into the job, from university courses to airlines' own training schemes; private training will set you back as much as £50,000 to £60,000.
"I most enjoy the variety of the job, working as a team, to a schedule, with the responsibility of safely transporting hundreds of people to their destination. I would advise aspiring pilots to thoroughly research training routes, understand the serious financial outlay required with no guarantee of a job after training and to consider other routes such as flight instruction."
Not all CEOs are making millions - but they're doing pretty nicely on average. There's no clear route into the job; an MBA can help, but many bosses have worked their way up from the bottom and many simply started their own firm.
"There is an old saying, it's very lonely at the top, which is usually the case for a CEO. You're the leader and you're responsible for everything, meaning you take the credit for the successes and feel the most pain for the companies' failures."
Most air traffic controllers train through National Air Traffic Services (NATS), which has programmes for college leavers who have studied at BTEC ND/HNC/HND level, university students on a sandwich year and graduates. NATS says the most important attribute for acceptance on a course is natural aptitude.
"Much of the time, the job is routine and capable of being done by many people. What you are paid for, however, is your ability to make the right choices and decisions under extreme pressure."
The high pay reflects both the heavy workload and the length of training required - a five-year degree course in medicine, a two-year foundation programme of general training and then another three years specialist training.
"You will get paid well and (despite recent changes!) you will get a very good pension. You will, however, work hard for your money with less recognition than previous years."
This is a job where most people work their way up, although qualifications like the Chartered Institute of Marketing's Professional Diploma in Marketing or the Institute of Direct and Digital Marketing's Diploma in Direct and Interactive Marketing can help. You'll probably need three or four years' experience before you can move into management.
"It's great working in such a varied job - there's something new every day. I enjoy the travel, too. But it's fast-paced, very hard work, and there's a lot of technical data analysis work involved."
It's not surprising that IT and telecoms directors earn good money. The job requires both business and technical skills, and the stakes are high: smoothly-running IT systems are crucial for most businesses and the cost of getting things wrong is high.
"It's a high-pressure job, and the hours can be unbelievably long, but it's extremely rewarding when a project goes well. The biggest problems are staying on top of changes in technology and being clear about what's actually achievable within a budget."
Financial managers and directors need to be qualified accountants and, particularly in larger organisations, have strong general business skills. And the job carries huge levels of responsibility, from keeping the company in good health financially to making sure it complies with the law.
"What I enjoy about the job is the way it's central to the business, the way I'm involved in creating long-term business plans. Compliance [with regulations] can be a bit of a pain; it takes a lot of hard work."
Until recently, the only way to become a senior officer was to work your way up through the ranks. Each police force sets its own recruitment process and selection policy, though there's a basic national framework for evaluating competency. This year, though, the College of Policing has started appointing superintendents from outside the force - so you might be in with a chance.
"I love the opportunity to take on a vast array of roles which would never be possible in a civilian organisation and to progress through a clearly defined promotion structure, should I prove to be good enough. The training I have received has been quite brilliant, enhancing my life skills as well as my ability to do my job well."
If your vision of a bank manager is of a middle-aged man in a panelled office dictating stern letters to his secretary, think again. It's now about managing a team and, especially, attracting new customers and monitoring branch performance. There are two ways to get to be one: either through a bank's graduate scheme, or by starting off in a customer service role and working your way up.
"For me, what's great about working in a branch is that anyone could be a branch manager, you don't have to have a certain skill set. Having a background in customer service, whether it's in a bank or with another retailer, certainly helps. Some other skills that would help are organisation, patience, tolerance and empathy. After 27 years I can genuinely say that that not only do I love coming to work every day, I have also made lifelong friends here. For me, it's not just a nine-to-five job."
Once you're qualified as a teacher, it's a question of working your way up by gaining extra responsibilities - by becoming a head of department, a head of year, or a specialist in something like special educational needs. At head teacher level, the job is far less about teaching itself, and far more about managing staff and budgets and creating a productive, disciplined learning environment.
"It's a common complaint that teaching is all about performance targets these days, and there is some truth in that. It's a question of balance, though. The most rewarding part of the job is knowing that you're bringing the best out of every single child by creating an environment where they feel safe and motivated to learn."