The British public is yet to understand “the scale of Labour’s ambition on the economy”, one of Keir Starmer’s most senior shadow ministers has said, adding that the party needs to explain how it will be the most interventionist government for a generation. Jonathan Reynolds, the shadow business secretary, said that the party had not yet fully communicated the “sum of its parts” in terms of how a series of technical policy fixes would translate into the ambitious transformation of the economy that the party will attempt to achieve. In an interview with the Observer, Reynolds said he believed Labour was now the “party of business” and invited any industrial leaders to meet him and “kick the tyres” on its commitment to turning around the economy. He said that Labour’s pro-business drive was completely different from the “prawn cocktail offensive” under Tony Blair, as businesses now wanted reassurances that Labour would change the way the economy was managed rather than reassurance that they would stick with the approach of their predecessors. He conceded, however, that the shadow cabinet now needed to use the 18 months before the next election to explain how Labour will be more interventionist than both the previous Tory and New Labour governments to revive the economy. He said the process had begun with Starmer’s “mission” to secure the highest sustained growth in the G7. “Where we are now is at a level of public support and business support which I’m not sure many people thought we could have delivered in the aftermath of 2019 on this timescale,” Reynolds said. “One thing we’ve struggled with, in my view, is that we’ve got a lot of very good policy that maybe hasn’t yet described the sum of its parts. In other words, I think what Keir’s missions do, especially the mission on the economy, is to take a lot of existing policies and explain them in a way that comes across with a degree of ambition I think we need, and that we can add to over the next 18 months to help deliver. “I feel people do not yet understand the scale of Labour’s ambition on the economy. I think we’ve got some components in place, which represent a very different approach to the economy from what we’ve seen , not just from the Tories but actually from the last Labour government. To deliver things like net zero, you have to have a more active state. “As it stands, people maybe don’t appreciate that to the same degree that those of us inside the shadow cabinet do. But be in no doubt that we are talking about an economy that will deliver for working people to a much greater extent.” Reynolds also said that Labour could achieve “significant improvements” to the post-Brexit relationship with the EU, and rejected suggestions that Labour lacked political courage in talking about the problems Brexit had created. He declined to say that he believed Rishi Sunak doesn’t think paedophiles should be jailed – a controversial claim made in a Labour attack ad. However, he backed the campaign’s attempt to hold Sunak to account for the Tory record in government. “It’s important that Rishi Sunak is held accountable for the last 13 years of Conservative government,” he said. “That’s what the campaign does, and I do think that is fair. I will always say I think civility is important in politics. My natural comfort zone would be a debate in detail on the issue or policy area. But accountability is important as well.” Reynolds also announced that Labour will tackle the issue of late payment, which sees smaller companies left unpaid by bigger businesses for months on end. The issue has been a problem for decades. However, he said Labour’s plan would finally tackle the issue by forcing big companies to reveal how quickly they are paying suppliers as part of their annual reports. New analysis by Labour of official data found that more than 1m businesses across the UK saw the number of unpaid invoices from customers increase over the last six months. The figures are based on a business survey by the Office for National Statistics.