They count among their network such luminaries as Bill Clinton, Peter Mandelson and the Queen. Their business empire boasts a turnover equivalent to the GDP of a small country. They are famously reticent about discussing their business and private lives.

But that has not kept the Hindujas, one of India’s most successful business families, out of the headlines over the years for everything from their role in a major bribery scandal to one of the most opulent and expensive weddings ever held.

The four Hinduja brothers — Srichand, Gopichand, Prakash and Ashok — have long been known in their homeland for their savvy business acumen. Born into wealth accumulated by their businessman father, the brothers steadily expanded their assets across the globe with substantial stakes in global finance, telecommunications, film and oil.

Srichand and Gopichand moved to London in 1979, from where they began to expand their family’s import/export business and became major contributors to both the Conservative and Labour parties. Prakash moved to Geneva, where he gained a foothold in finance, while Ashok remained in Bombay, where he oversees the family’s Indian-based business.

Despite their success, it was not until 1990 that the famously private brothers became household names in one of the biggest corruption cases to hit India since its independence. Srichand, Gopichand and Prakash were accused of receiving millions of dollars from Bofors, the Swedish arms company, in return for persuading the Government of Rajiv Gandhi to buy 400 field guns.

The case had already brought down the Gandhi Government and now the brothers’ empire also seemed threatened. A decade later, a Hinduja-related scandal reached British shores when Peter Mandelson was accused of helping the two London-based brothers gain British citizenship in exchange for a donation of £1 million to his Millennium Dome project. Gopichand and Srichand were refused British passports on their original application in 1990, but were granted them in 1997 and 1999 respectively, soon after offering to help to fund the Dome project. Mr Mandelson was forced to resign over the scandal, although he was later cleared of any wrongdoing.

In 2005, an Indian appeal court cleared the brothers in the Bofors case after a legal process costing £32 million and “huge economical, emotional, professional and personal loss to the Hindujas”, the judge said.

Any financial damage the case did appears to be only temporary. Last summer, the four brothers acquired one of London’s most expensive and sought-after properties, previously owned by the Queen. The brothers paid £58 million for a 100-year lease on the 60-room property at Carlton House Terrace on the Mall, and plan to spend another £40 million to 50 million converting it for use by their joint families.

On completion, its value will outstrip the £70 million Kensington Palace Gardens home of fellow Indian-born billionaire Lakshmi Mittal, the most expensive home in Britain. In October, the family gathered in Bombay to host the wedding of Prakash’s youngest daughter, Renuka, in an ostentatious ceremony aimed at signalling to the world that the family’s troubled fortunes have at last turned a corner.

Their largesse extended to full Indian costumes, air fares, luxury hotel suites and chauffeur-driven cars for their 3,000 guests, many of whom were business associates flown in from around the world. The success of the occasion sent out a clear message that the Hindujas were back in business.

The size of the Hindujas’ assets remains a closely guarded secret, although it has been estimated to be in the realm of £8 billion. As befits the tight-knit family, its assets are not divided among the brothers, but communally held by the House of Hinduja.

While they may have become more wary of making donations to political parties, they remain prolific philanthropists through their Hinduja Foundation. Their philosophy is summed up in their family business motto: “My Dharma is to work, so I can give.”