There was an elephant in the room as hundreds of business leaders gathered at the Oval cricket ground in south London to hear Labour’s pre-election pitch to captains of industry on Thursday. The opposition party had made much of its plan to sweep away zero-hour contracts and reverse many of the Conservative government’s employment laws in recent months. But it was barely mentioned at the conference until Keir Starmer fleetingly declared in his speech that not everyone was likely to be on board. Starmer said it was a key part of “levelling up workers’ rights in a way that has not been attempted for decades”. The policy received a mixed reception. One senior business executive, who asked to remain anonymous, was uncertain about the promised employment laws giving staff greater protection. “There is an intent, but still very little detail, so it is something where we don’t really know the knock-on effects,” they said. A director of an energy company said that while most of his employees were on high wages and generous terms of employment, they used contractors who might be affected. But Peter O’Driscoll, the managing director of the parking app RingGo, said it would have no effect on his business, which mostly employs specialist technology workers and complies with the high standards set by its main partners – local councils. “We are part of a group run out of Sweden and it’s safe to say the main business has much higher standards than the UK already,” he said. Helen Brocklebank, the head of the lobby group Walpole, which represents 250 luxury brands including Burberry and Aston Martin, said her members were unlikely to be affected. “Our members employ highly skilled people who are valued in the way Keir Starmer talked about,” she said. More than 400 executives attended Labour’s conference, which provided a succession of shadow ministers for an eager audience keen to find out what is in store from the opposition before the general election this year. A morning breakfast with the shadow City minister, Tulip Siddiq, set the tone, with some of the biggest beasts in the financial sector on the panel talking about how Labour could overcome the instability and uncertainty caused by Brexit and the prospect of four UK prime ministers in as many years. Brioche rolls stuffed with sausages and bacon were served to accompany Siddiq’s speech, in which she spelled out how Labour would seek to boost the City and promote the financial sector more broadly. Small but tasty portions remained the theme for the rest of the day, and not just in relation to the food. Speeches were kept short, with plenty of time for questions at the £1,000 a head conference. Rachel Reeves’s commitment to cap the level of corporation tax at 25% was followed by some challenges to her plans for £28bn of green infrastructure investment. She stuck by the pledge, but in terms that meant it could be watered down if Jeremy Hunt spends all the Treasury’s spare cash in his budget next month. Sponsored by the financial data provider Bloomberg, and with Microsoft, Google and the heads of all the leading business lobby groups in attendance, there was a big company theme at the conference. Against the backdrop of the cricket pitch, the National Grid chair, Paula Rosput Reynolds, interviewed Starmer after his speech and the question of the £28bn green investment pledge was raised again. Starmer joked that it was Reynolds’ company that was going to take the UK towards an electric future and he should be asking questions of her. In the time left for audience participation, Starmer was pointedly asked what he would do for small and medium-sized firms, but while he lauded the efforts of owner-managers, it was clear his need to boost the economy would rely on seismic shifts in investment that only the major corporations can deploy. Dan Hogan, a director of the communications firm Blakeney, said many of his clients were energy companies and feared the £28bn pledge would be rolled back. “But the message of stability and certainty if Labour comes to power is one they will like,” he said. O’Driscoll said he was at the conference to check with Labour’s transport team that a government plan to develop a national charging scheme that brings together parking and EV charging would be embraced. Like so many projects under the current administration, it won’t be finished before the election and would need the approval of a future Labour government. “It’s a huge project that will be a big step forward, if it can continue,” O’Driscoll said. The evening ended with a party for 200 ambassadors and investors who were expected to be offered wine and beer, but not champagne. Maybe Labour’s budgeting in opposition is much as it would be in government.