A Conservative former cabinet ­minister who took donations from the billionaire boss of the JCB digger dynasty – including a £7,000 trip on his VIP private helicopter – oversaw decisions to award his family’s business empire millions in taxpayer-funded green energy grants.

Claire Coutinho also posed for ­pictures promoting Lord Bamford’s personal £100m hydrogen engine project and accepted a £7,500 donation from JCB to her local election campaign while she was the energy secretary in Rishi Sunak’s government.

The revelations raise questions about possible conflicts of interest for the East Surrey MP – who is now serving as shadow secretary for energy security and net zero – and shed light on a wider pattern of donations from the JCB empire, which has given £300,000 to the Conservatives in 2024 alone.

While the Tories were in office, Coutinho’s Department for Energy Security and Net Zero was responsible for allocating funding from the Net Zero Hydrogen Fund and other funding pots intended to boost green energy initiatives.

The family of Lord Bamford, a longtime leading donor to the Conservatives and a friend of former prime minister Boris Johnson, has invested heavily in hydrogen and lobbied for government spending on infrastructure projects.

The Observer’s investigation has established that Coutinho met personally with Bamford and organisations linked to him before and after key funding decisions that benefited his family’s business empire.

In September 2023, a consortium led by Ryze Hydrogen, a company owned by Bamford’s son Jo – heir to the family fortune and a director of JCB’s holding company – won £3.2m from Coutinho’s department to provide hydrogen refuelling to construction sites. JCB has a business relationship with Ryze, jointly signing a multibillion pound deal with an Australian mining company to supply green hydrogen to the UK.

Two months later in November 2023, Coutinho met with the Centre for Policy Studies, a free-market thinktank of which Bamford is a director, to “discuss the future of energy security”. Coutinho declared the meeting but did not say who it was with.

In December 2023, a project by Hygen, another company owned by Jo Bamford, was one of 11 granted a slice of £90m in government grants from the Net Zero Hydrogen Fund.

And in February 2024, a Bamford-linked project, including Ryze and Hygen, was granted a share of £21m funding to build a “network of hydrogen production and refuelling stations” in Suffolk.

Soon after, in May 2024, Coutinho travelled to JCB’s headquarters in Staffordshire for a meeting to discuss Bamford’s £100m project on hydrogen combustion engines. During that trip she “met JCB chairman Anthony Bamford who is personally spearheading JCB’s hydrogen developments”, and posed for photos in a JCB hard hat and hi-vis vest.

The meeting was publicised by JCB on social media and in a press release, republished by media outlets with the headline: “Energy secretary inspired by JCB’s hydrogen engine innovation”. The press release also included an endorsement from Coutinho. “It was terrific to visit JCB to see their pioneering hydrogen combustion engines powering a new generation of diggers,” she said. “Countries around the world are queuing up to work with brilliant UK businesses, like JCB …. It is incredibly inspiring to see the levels of innovation, dedication, and enthusiasm throughout JCB.”

The following month, on 25 June, J C Bamford Excavators gave £7,500 to Coutinho’s Conservative association to help with her re-election campaign.

The relationship has continued since the Tories lost power. In the latest register of interests, Coutinho declared that she and a member of staff took helicopter flights to Staffordshire and back, worth £7,182, on 19 September for a meeting at JCB’s headquarters.

Whether Coutinho met Bamford personally on that trip is unclear because her declaration said only that it was for a meeting with JCB

According to flight logs from a global tracking service, the helicopter flew from London and was a Sikorsky S-76, which is popular among state leaders and VIPs.

There is no suggestion that the grants to Bamford family companies were awarded improperly or that correct processes were not followed.

But transparency campaigners said the pattern of meetings, donations and funding decisions created the impression of a “cosy relationship” that raised ethical concerns.

Rose Whiffen, senior research officer at Transparency International UK, said the findings raised “­serious questions about the potential influence of outside individuals over policy”.

“When decision-makers repeatedly accept meetings, hospitality and contributions from the same donor, it gives rise to a perception that a cosy relationship exists,” she said.

“Ministers and shadow ministers should always be cautious when accepting gifts and hospitality from outside interests – even more so when the source of these donations has a direct interest in their ministerial brief.”

Tom Holen, programme manager for energy transition at InfluenceMap, which tracks climate lobbying, said current UK rules allowed “concerted corporate engagement with politicians to happen under the radar”.

The Green party’s deputy leader, Zack Polanski, said: “The generosity of big business donors to political parties always comes with an unacceptable price tag around perceptions of buying influence.”

Coutinho was also criticised over her choice in September to travel by “climate-damaging” helicopter, given her ministerial brief covers cutting carbon emissions.

With the JCB helicopter thought to burn almost 480 litres (about 105 gallons) of fuel an hour, her £7,182 return trip could have pumped out an estimated two tonnes of CO2. Had she gone by train, it would have cost about £90, taken approximately two hours each way – plus a 10-minute car journey – and caused a fraction of the pollution. Carys Boughton, a campaigner at Fossil Free Parliament, said the helicopter trip was the “toxic cherry on the cake” and described the donations as a “particularly obvious conflict of interest”.

She added: “As the former energy secretary and now shadow secretary of state for climate change and net zero, Coutinho should not be allowed to take gifts and donations from companies that are pushing for the approval of energy projects that she has prospective influence over.” .

The donations to Coutinho are part of a wider pattern of the Bamford family lavishing cash on the Conservative party. Data from the Electoral Commission shows that Bamford, his relatives and companies in his family’s business empire have given at least £10.2m to the Conservatives since 2001.

They include personal payments from Bamford and Jo Bamford to Conservative central party and local campaigns, as well as at least £2.9m from JC Bamford Excavators in the last five years alone.

JCB has previously paid for MPs to travel on its helicopters and private plane, including funding a helicopter trip for Tory backbencher Jacob Rees-Mogg in April 2024. Rees-Mogg, who lost his seat at the general election in July, briefly served as energy secretary in Liz Truss’s government in 2022.

Bamford also has close links to ex-prime minister Johnson, reportedly letting him stay at his properties in Knightsbridge and the Cotswolds and giving him £23,853 to pay for food and flowers at his wedding party.

The Bamfords are one of the wealthiest families in Britain, with an estimated worth of £7.65bn, according to the 2024 Sunday Times rich list. Last year, JCB paid a £300m dividend to Bamford and his family after pre-tax profits rose by 44%.

Companies owned by the Bamfords made recent appearances at both the Conservative and Labour conferences. The family are among the most vocal advocates for adopting hydrogen in the UK and have called on the government to invest in infrastructure as well as hydrogen-fuelled forms of transport such as buses, trains, ships and aircraft.

Environmental campaigners have raised concerns about the promotion of hydrogen for tackling the climate crisis, particularly in sectors such as heating and transport, because it can compete with more efficient technologies, including heat pumps and electric vehicles. Some fear promises of “green” hydrogen, made using renewable energy, are part of a “bait-and-switch” strategy by the fossil fuel industry to secure the future of the nonrenewable form of the fuel, which is made from natural gas.

Before Coutinho was appointed energy secretary, the Conservative government gave its backing to other projects linked to the Bamford family, including funding for Wrightbus, a division of the Bamford Bus Company, which made the world’s first hydrogen-driven double-decker, and a special authorisation for JCB’s hydrogen-powered digger to be tested on UK roads.

JCB and the Conservative party declined to comment on the donations, meetings and government funding. Coutinho’s office did not respond to emails or calls.

JCB has previously said its hydrogen engines are “super-efficient” and a vital solution for hard-to-decarbonise sectors such as construction. In an article last year, Bamford said JCB’s commitment to reducing emissions “goes back almost 25 years”.

Hygen said it delivers hydrogen projects to “drive net zero”, while Ryze said it supplies “clean” hydrogen and infrastructure to “accelerate the energy transition”.