I am withdrawing from the race to be the leader of the Labour party. I will not be nominating any other candidate, but I am announcing my withdrawal now so that the MPs who have supported me have the opportunity to nominate another candidate, should they wish to do so.

I’m grateful to the people who told me I inspired them to begin their own leadership journeys. My “bootstrap Britain” story resonated with many who have overcome disadvantage to achieve their goals. I am proud to have played my part in opening up the debate about why Labour lost, and I look forward to working with the next leader to build a society where hope, compassion and economic competence exist side by side.

Much has been said over the past few weeks about why Labour lost the election and our problem with business: the anti-business rhetoric and tone of the party’s message; the fact that business people would be invited to write reports as public relations exercises, their recommendations left to gather dust on Westminster bookshelves; the fact that not a single CEO of a large company would come out to back Labour’s stance on not having an EU referendum during the election.

I realised we had a big problem with business when Labour introduced a devolution policy on transport in Manchester late last October. We were announcing that regional transport bodies would have the same powers to regulate their buses as the mayor of London, who operates a fully tendered bus system under Transport for London. For passengers it would mean proper oversight of bus routes. For the taxpayer it would mean that more of the £2bn of public subsidy to buses would be ploughed into bus routes, which would help local passengers, local businesses and growth. It was a good example of how to deliver better public services when there is less money around. But the new policy could also have meant a reduction in the profitability of the bus companies. I had good relationships with the five big bus companies, so we rang round to brief them as a courtesy.

I was told that we wanted to 'pick a fight' with businesses, to show Labour tackling vested interests. I was dismayed

At Manchester town hall I explained that my team had done this and I was asked why. So I explained that we would need the bus companies to deliver the reforms we wanted to make. That’s when I was told that what we wanted to do was to “pick a fight” with these businesses, to show that Labour was tackling vested interests. I was dismayed. Bus subsidy was a complex area and if we wanted reform without transport chaos, we would have to work with the companies not against them.

In the end, the event was scuppered by Ed Miliband’s encounter with a young woman begging on the street. Our new bus policy was barely mentioned in the next day’s papers. But that exchange in Manchester town hall crystallised for me that the leader’s office did not understand business and didn’t understand what business needed from government. I spent 10 years working with small business people at London Enterprise Agency and Cranfield business school. I learned from them that Labour cannot be the party of working people and then disapprove when some working people do very well for themselves and create new businesses, jobs and wealth.

The Organisation for Economic Cooperation and Development recently warned that inequality is a threat to economic growth. So Labour must work in partnership with business – the strong social partnership model used in countries like Germany could be one way of tackling Britain’s productivity gap. Labour is the only party that can and must make the hard-headed business case for tackling inequality. There are now 1,500 living-wage employers. That is something we should celebrate and encourage. Companies know that they need customers with money in their pockets and sustainable supply chains if they are to succeed. The horsemeat scandal was a wake-up call to the big supermarkets. They fought a race to the bottom on price, forgot that quality matters to customers and have seen their share prices take the hit as the market changed and they failed to adapt.

Labour must want big business to succeed – it’s where many of the jobs are – but pay and conditions must be fair. And Labour must want small business to succeed: it’s where innovation and creative thinking take place. All big businesses started out small. But dividing them into “producers” or “predators” alienates businesses, large and small.

Labour lost the election because – while people trust us to run their schools their councils, their hospitals – they do not trust us to run the economy. Tackling inequality is why the party exists. It’s in our DNA. But the next Labour leader will have to show that Labour understands the problems facing the UK’s five million self-employed people, sole traders and small businesses. That understanding must also run through our party’s DNA like a golden thread if Labour is to win in 2020.

It is right that Labour should change its stance on the EU referendum. Not to have done so would have been absurd, given our election defeat. But the referendum is a clear danger to British jobs, growth, business and investment, as well as workers’ rights and environmental protection. Labour should make the principled and unambiguous case that staying in the EU is in our national interest. As well as a Labour in Europe campaign, we must play our full part in a cross-party pro-Europe campaign. The prospect of the Tories once again tearing themselves apart over Europe offers Labour a short term tactical advantage. It’s why David Cameron is determined to have the referendum as soon as possible. But that should not blind us, as progressives, to where Britain’s national interest lies – in the EU, making the case for investment in research and development, green energy and tackling unemployment and climate change.