The building site where you have to slip the foreman £50 out of your wages; the warehouse where they send you home early, without pay, when they run out of books to pack; the container port where zero-hours contracts are driving security guards to mental stress and family breakdown. This is the reality of the British workplace, as told by workers in precarious jobs from the Unite trade union at the TUC conference last week.

British workers are living through the longest period of wage stagnation for 150 years – and the root cause is the entrenched powerlessness those Unite activists described. Minimum wages, gangmaster licensing laws and the legal right to form trade unions mean nothing when managers wield arbitrary power in the workplace.

As the Labour party revs up for its annual conference it should have one image in its mind: the urgent/important grid known to everyone who has been on a management-for-dummies course. You focus on what’s both urgent and important first, but always push the important stuff to the top of the pile.

If Labour comes to power amid a Tory collapse, there will be many issues clustered into the “urgent and important” category: restoring order to the Brexit process, preventing an attack from the financial markets, an emergency budget to kickstart growth. But if there is one policy area that should define the first 90 days of a Corbyn government, it is workers’ rights: boosting the power to bargain wages upwards and to end precarity at work.

When Blair came to power, it took him two years to enact a law allowing workers to ask for union recognition. Numerous business lobby groups – in one consultation after another – predicted doom should workers be given any extra rights at all.

This time, the consultation should be with the electorate only. Labour’s June 2017 manifesto contained a long list of workplace reforms, but in the first 90 days it should focus on just three: banning zero-hours contracts, hiking the penalties for exploiting people via bogus self-employment and awarding all workers, including part-time and temporary ones, full employment rights from day one on the job.

Precarious work exists because, for 30 years, small- and medium-sized companies have been created with business models that can only work if the abuses described above exist. Labour’s workplace reform will be a battle to change the behaviour and mindset of a whole layer of business owners.

I’m talking about the hair salons where everyone is “self-employed”, yet there is a central cash register and a strict management structure. Or the cleaning firm where an unseen manager distributes shifts via text message, and redundancy takes the form of no more text messages. Or the fast food giant where workers are encouraged to vote their colleagues out of a job if they are not being cheerful enough. You have to attack these abuses from above and below – both by legislation and face-to-face persuasion.

And that, in turn, is why Labour’s democratisation and transformation into a social movement has to continue and deepen. It is one thing to raise £11bn through corporation tax and spend it on abolishing student fees: that’s a classic administrative measure in which both the winners and losers are bystanders. It’s another thing to empower every cleaner, security guard, construction worker and home carer with the right to say no to an abusive boss.

For that, you need a social movement operating in the deep roots of the economy: a network that can spread behavioural change, setting new norms and creating new mindsets. You need a big poster in every Starbucks and every minicab office saying: the workers here have rights, here’s the number you ring if they are not observed. And a union rep in every workplace.

In turn, the scale of the change means Labour has to field a team of MPs in the Commons who will not wimp out under pressure. This year’s battle – over the right to nominate a left leadership candidate – must be the prelude to the real fight: for mandatory reselection of parliamentary candidates.

If Labour comes to power, it will do so in an atmosphere of crisis. Even if there were no crisis to start with, the Daily Mail and its broadcast echo chamber would create one. The last thing we need, then, is for a group of MPs to suddenly decide the manifesto was too radical, that consultation is better than action, that their own high principles demand they side with the Tories to defend the business models of Amazon, Starbucks and the rest.

Sadly, workplace reforms that would seem mild in other countries will seem revolutionary here, after 30 years of deregulation. Any Labour MP, current or prospective, who is not up for that revolution should be replaced.

And for that, Labour members need the right to choose their candidate. That rule change may not happen this year, but it needs to remain the goal. Not for the sake of a principle, but for the sake of millions of low-paid, bullied and precarious workers for whom a Labour government carries the only hope of change.