Businesses are expected to cancel their attendance at this year’s Conservative conference in unprecedented numbers, in a chastening snub that could also undermine the party’s ability to raise funds.

The annual gathering, due to be held in Birmingham from 29 September to 2 October, would usually attract corporate attendees willing to pay tens of thousands of pounds to get close to MPs with influence over policy.

But Labour’s landslide general election victory means this year’s event is on track to be the least popular in living memory, according to several public affairs firms and business leaders.

They said the conference was likely to be less well attended by business leaders than the one held after Tony Blair’s 1997 victory and even Labour conferences under Jeremy Corbyn’s leadership.

“The lack of appetite among business for the Conservative party conference is no doubt fuelled not just by the attractiveness of Labour, but also a realisation that the Conservative party is at a real inflection point,” said Katherine Morgan, head of public affairs for Europe at the global advisory group DGA.

“The challenge for the Conservatives will be ensuring that September marks the beginning of the journey towards re-establishing their credentials as ‘the party of business’.”

Several large agencies are understood to have cancelled dinners they were due to host at the event or scaled back the number of people they are sending.

One firm contacted said that only one company out of its 70 clients was planning to have a presence in Birmingham.

Jon McLeod, a partner at the strategic communications consultancy DRD Partnership, said: “While the Labour conference will be the bunfight of bunfights, with corporates piling in from all directions, there is something to be said for a low-key presence at the Tory conference this year if only to take the temperature on what direction the party is set to take once it rises from the ashes.”

Another leading public relations executive, who asked not to be named, said they had spoken to two corporate clients about their possible attendance. “One said they had no interest, the other is going but said it’s going to be ‘like a wake’,” the adviser said.

Any significant drop-off in numbers would be likely to exacerbate the Conservative party’s funding problems, after a raft of mega-donors switched loyalties in the run-up to the election.

One leading figure in the tourism and hospitality sector, who asked not to be named, said: “There isn’t much to be gained from corporates being there,” adding that the resulting loss of income would hurt the party.

“There’s a funding issue. There will be some things pre-contracted that they’ll hold people to. Some [businesses] may be tied in to attending and may not want to do it now.

“I’d expect this conference to be the lowest attendance I can remember. Even in ‘97 it wasn’t catastrophically bad.”

The party charges fees for events and exhibition stands, with prices set out in a brochure that includes a foreword from Richard Holden, who was party chairman when it was written but has since resigned that post after nearly losing his seat at the election.

Each ticket to the conference’s dedicated “business day” (Monday 30 September this year) sells for £3,500, while booking rooms such as the Churchill Theatre and the Thatcher Theatre can cost up to £10,000. Firms who want a stand in the exhibition hall can pay up to £55,000.

The latest accounts for the party, from 2022, show that it spent £4.3m on its conference that year and made £6.3m, a notional profit of £2m.

“[Conferences] are valuable to all parties,” said Fraser Raleigh, head of public affairs at communications firm SEC Newgate. “You saw that during the pandemic when they couldn’t meet physically. The parties see them as important fundraising moments.

“I think people are looking at their plans and thinking about whether to send fewer people. Given that these things are priced quite far in advance, I’m not sure refunds are likely to happen.”

He said the conference could be saved from total desolation if businesses see it as a chance to get close to the party’s next leader. “There’ll be some political interest if, as it looks like it might, the leadership contest is coming to a crescendo at that point, if conference is used as the hustings for the final two.

“Labour are in a commanding position but volatility of voter loyalty has been growing so it would not be wise for business to assume the state of things now will be the state of things for ever.”

A Tory party spokesperson said they were not concerned about attendance levels at this year’s event. “The Conservative party conference will be returning in full force this year, including its business day,” they said.

“So far we have already seen significant interest in this, with high demand for tickets and partnerships and a full exhibition hall. Business day partnerships in particular are already significantly up on last year’s conference.”

If attendance does fall, the leadership contest triggered by Rishi Sunak standing down after his election could limit any impact on local bars, hotels and restaurants in the Westside district where the conference will be held.

Mike Olley, general manager of the Westside Business Improvement District, said: “When they first came they were looking down their noses at people. Since then, they’re a decent bunch. They spend well and they’re not a bunch of Hooray Henrys any more.

“I don’t think that to us we’ll see a turndown in numbers. That’s more about the people who put the trade stands on.

“The trade hall won’t be packed maybe, but plenty of businesses will turn up because they know they’ll be back in power eventually.”