The UK's Labour opposition vowed Tuesday to be both "pro-worker and pro-business" after winning the backing of 120 industry leaders as the party tries to oust the Conservatives in the upcoming general election.

In a speech at a Rolls Royce factory in central England, Rachel Reeves -- who is set to become finance minister if Labour wins power on July 4 -- argued it was now "the natural party" of business.

"I'm not one of those politicians that thinks that the private sector is a dirty word, or a necessary evil," Reeves, centre-left Labour's finance spokesperson since 2021, told an audience of business figures.

"I know that economic growth comes from success of business -- large, medium, and small. Indeed, there is no other way.

"I want to lead the most pro-growth, the most pro-business Treasury that our country has ever seen with a laser focus on delivering for working people."

Her speech came hours after the 120-strong coalition of CEOs and other senior business figures endorsed Labour in a joint letter, saying that it was "time for a change".

The grouping argued the UK economy had been "beset by instability, stagnation and a lack of long-term focus" and the country lacked "the skills and infrastructure it needs to flourish".

"Labour has shown it has changed and wants to work with business to achieve the UK's full economic potential," the letter published in The Times stated.

"We should now give it the chance to change the country and lead Britain into the future."

Its signatories include senior figures in various industries, from banking and advertising to retail and technology.

Jimmy Wales, the founder of Wikipedia, and Tom Kerridge, the restaurateur, are among the notable names on the list.

  'Foregone conclusion'? 

 Labour has been at pains to show it has moved decisively away from a less business-friendly period under former leftist leader Jeremy Corbyn.

He presided over its worst election result in decades in 2019, and quit as leader soon after.

Corbyn's successor Keir Starmer and Reeves have spent the subsequent four years wooing business figures.

The Conservatives -- in power for 14 years -- have traditionally been more trusted by Britain's business community, but have seen that reputation dented post-Brexit.

Ex-prime minister Liz Truss's disastrous 49-day tenure in 2022, when her tax-cutting agenda spooked markets, has been blamed in particular for shredding confidence in the party's reputation for economic competency.

Prime Minister Rishi Sunak called the election with the Tories lagging well behind Labour in the polls.

His campaign has made a faltering start, with a post-WWII record number of its MPs announcing they will not run and signs of infighting erupting into public view.

Also campaigning in central England Tuesday, Sunak touted the Conservatives' latest policy announcement, billed as a £2.4 billion ($3 billion) tax break for pensioners.

Older voters are typically far more likely to vote for his party, and have been protected from the country's crippling cost-of-living crisis in recent years more than others.

The policy follows the Tories announcing Sunday they will bring back a form of national service if they retain power, in an apparent bid to maintain the support of its disgruntled right-wing base.

In his stump speech Tuesday, Sunak sought to utilise his underdog status in the race while attacking his Labour rivals.

"(They) want you to think that this election is over. Well, you know what? I don't think this election is a foregone conclusion," he insisted.

Labour received a further boost Tuesday when police announced that deputy leader Angela Rayner would face no further police action over claims she avoided tax on the sale of her house several years ago.

Elsewhere, the Liberal Democrats leader Ed Davey fell into Lake Windermere while paddle boarding as he outlined his fringe party's plans to tackle Britain's sewage crisis.