Notoriously camera shy, Rowland is said to have refused to give the Conservatives a photograph of himself. The only publicly available image of Rowland, a man whose business interests have spanned the globe, is a black and white photograph of him smoking a cigar, printed in the Observer in 1971.

The story was about his return from Paris, where the 25-year-old had gone into tax exile after selling his interests in Fordham Investment Group for £2.4m. The accompanying description of a “wheeler dealer extraordinaire” with a penchant for fat cigars is one that would not seem out of place almost four decades on.

Rowland, along with his son, is now estimated to be worth more than £730m, a sum that makes them jointly the 25th richest people in the country. He was also set to become one of the country’s most politically influential figures, as fundraiser-in-chief for the Tories.

The announcement by Conservative party central office that Rowland would not be taking the post due to his “developing business interests” capped a tumultuous summer for the property developer who, soon after the Tories announced that he would take over as their treasurer, became the subject of a string of stories in the Daily Mail that sought to paint his business dealings and personal life in a controversial light.

The son of a London scrap-metal dealer, Rowland is said to have left school without a single O-level. Aged 15, he was convicted of petty larceny at Wimbledon juvenile court, having stolen goods worth £2. That sum would soon pale into insignificance for Rowland, who within five years had turned his life around, bought a house and become a millionaire.

By his early 20s he was renowned for his business acumen and fierce approach to takeovers, later acquiring a business empire that, in the 70s and 80s, expanded into Europe and the United States.

As well as living abroad to avoid tax in the UK, Rowland reportedly used tax havens such as the Bahamas, Panama, Luxembourg and the British Virgin Islands for his business dealings.

The property tycoon has occasionally found himself in controversy.

One such occasion came in the late 80s, when Rowland participated in an attempt to take over Hibernian, one of Scotland’s top football clubs. The deal fell, however, incurring the wrath of the local MP, who tabled a motion in the House of Commons denouncing Rowland and David Duff, the lawyer he was apparently financing.

The motion accused the pair of involving the Edinburgh club in loss-making dealings, called for an inquiry into “recent wheeling and dealing”, and described Rowland as a “shady financier”.

Another noteworthy aspect of Rowland’s life has been his friendship with the Duke of York, which has dated back several years. Prince Andrew unveiled a life-size bronze statue of Rowland – reportedly showing him smoking a cigar in “vaguely Churchillian pose” – in the grounds of Havilland Hall, the largest privately owned estate on Guernsey, in 2005.

More recently Rowland appears to have decided to forsake his privacy and take an active role in British party politics. Electoral law prevents foreign donations, and last year Rowland returned to his native country from decades of tax exile, relocating to Mayfair, which enabled him to make a string of large gifts to the Tories.

Rumoured to have paid £20,000 for a portrait of the prime minister, David Cameron, at a Tory fundraising auction, his conversion to the Conservative party’s cause seems to have been absolute.

In a little more than a year he donated almost £2.8m, making him the Tories’ largest benefactor. Exactly why a man who had not shown much interest in the party for at least a decade became an enthusiastic supporter remains a mystery.

He started with a sum of £1m in June last year, and continued to give as the general election drew nearer. By June this year, Cameron had appointed him to be his party treasurer. Rowland pronounced it a “tremendous honour”.

That appointment, however, may have placed him on a collision course with the Conservative party’s better-known benefactor, Michael Ashcroft.

In the time Rowland donated more than £1m to the Tory party, Lord Ashcroft, through his corporate vehicle, Bearwood Corporate Services, donated around £100,000, although his support of the party dates back far earlier. Rowland’s sudden promotion is also said to have irked a number of senior Tories.

Not long after Cameron unveiled his new treasurer, a series of critical articles appeared in the Daily Mail. Many appeared to focus on Rowland’s private life, and delved into marital issues dating back decades.

A more serious accusation concerned pollution from a lead smelting plant in Idaho, America, alleged to be one of the country’s worst industrial pollution scandals. The pollution was said to have caused acute respiratory health problems among local children.

Rowland was not connected to the plant when the pollution occurred in the 1970s. His property company bought Gulf Resources, which owned the plant, more than a decade later, in 1989.

Rowland and others were accused of diverting company assets which should have been used to clean up the contamination. It is alleged that the money was used instead in a property deal in New Zealand. He and other directors were also accused of transferring company assets overseas when they should have been used to pay for the health insurance of former employees.

According to a lawsuit in the US in 1997, Rowland and other directors were accused of engaging “in a course of conduct designed to loot and waste the assets of the company”. It was alleged that “the defendants entered into a series of transactions by which they transferred Gulf assets into their control”.

It was also claimed that when concerns were raised, Rowland gave assurances that Gulf would “meet its obligations for employee benefits and environmental clean-up, assurances alleged to be false and fraudulent”.

Rowland has called the court allegations “unsubstantiated and false”. He has been quoted as saying: “There were multiple defendants in the case and it is customary in such American cases for extreme claims to be made.

An investigation has revealed how the group has raised close to a million pounds since 2007, using the money to lobby for a stronger relationship with Saudi Arabia, as well as arrange delegations to other parts of the Arab world.” …

… an exclusive MEMO investigation has revealed that nearly all of the CMEC’s financial backers have strong business interests in Saudi Arabia and its smaller Gulf allies, ranging from defence to manufacturing to energy resources. This suggests that the support by the CMEC for an unconditional relationship with Saudi Arabia could be driven by donor preferences, something that is denied by officials. …

… By far the most generous current backer of the Conservative Middle East Council, according to Electoral Commission records, is David Rowland, a controversial British business tycoon, political financier and Monaco tax exile. Rowland has been involved closely in helping to secure multi-billion pound defence deals between British firms and the Saudi Arabian government; he has given the CMEC nearly £350,000 since 2010. In 2011, Rowland offered his private jets to Prince Andrew for free, as the member of the British royal family visited Saudi Arabia to help secure deals for BAE Systems.

The investigation also revealed that in June 2015, Rosemary Said, the wife of Syrian-Saudi businessman Wafic Said, gave CMEC £20,000; back in 2008, the donation was much more substantial, at £100,000. Wafic Said, who was banned from making donations to Westminster political parties as he does not hold British citizenship, is reported to have played a key role as a “fixer” in arranging the controversial Al-Yamamah deals between BAE Systems and the Saudi Arabian government, using his extensive network of contacts within the kingdom. Records show that alongside channelling funds to the CMEC through his wife Rosemary, Wafic’s son Khalid, has also given £12,500 to the organisation. …

… Energy boss Abdul Majid Jafar is also a donor to the CMEC, giving the group £15,000 in January 2014. His company, Crescent Petroleum, is the oldest of its type in the Middle East, and has extensive interests in the UAE, Bahrain and Iraq, with a smaller footprint in Saudi Arabia.

The investigation has also revealed that a construction firm called International Hospitals Group has donated £40,000 to the CMEC in the past two years. The company has secured several multi-million pound contracts with the government of Saudi Arabia, and received as a result “various letters of acknowledgement [i.e. references]… from senior Royal Princes” within the House of Saud, with which the company enjoys a strong business relationship.

A former funder of the lobby group is Pierre Rolin, a financier who previously provided investment management services to a $1bn American property empire owned by Prince Abdul Aziz Bin Fahd, a prominent royal in the House of Saud. Details of the extent of this portfolio were revealed in 2012 by investigative journalist Seth Hettena. However, Rolin stopped donating to the CMEC in 2009, and shortly afterwards it was revealed that his financial advisory business to the Saudi prince had collapsed.

The MEMO investigation also showed that the CMEC received an £18,000 donation from the London-based PR firm Bell Pottinger, which has represented Saudi Arabia in a public affairs and advocacy role. Its other clients have included the Bahrain government; the company declined to comment when contacted by MEMO, although a spokesperson for the CMEC said that the donation had been made because Bell Pottinger “supported the aims of the organisation at the time.”

The Director of the Conservative Middle East Council, Leo Docherty, told MEMO that donations (and thus donors) had not influenced decision-making within the group. “No donor has given us conditions,” he insisted, “but any big business person in the Middle East has strong interests in Saudi Arabia. We see ourselves as making the case for a constructive relationship, but we acknowledge it’s not perfect.”