Marc Meyohas of Greybull Capital stands in front of the British Steel sign, 2016
Greybull Capital are the private equity firm who bought British Steel for a token £1 in 2016.
British Steel has now gone into official receivership after failing to secure government funding for its future, and now faces liquidation.
Brothers Nathaniel Meyohas, 46, and Marc Meyohas, 43, are part of a wealthy French family and made their fortune by investing in private equity.
The brothers set up Greybull in 2010 - but have been marred by a series of failures.
Up until the recent trouble with British Steel, the airline Monarch, which collapsed in 2017, was the most high-profile business to fall while owned by Greybull.
Nearly 1,900 workers were left redundant when Monarch went bust, forcing authorities to step in and help more than 100,000 holidaymakers get home - reportedly the biggest repatriation since World War Two.
Greybull had pumped £125million into Monarch in 2014 with hopes of preventing it from failure.
The fund had also bought My Local convenience chain for £25 million, only for it to collapse in 2016.
It was also part of a group of investors that backed the acquisition of Comet, shortly before it too collapsed - leaving the taxpayer with a reported £23million bill.
Greybull Capital are the private equity firm who bought British Steel for a token £1 in 2016 (pictured: Nathaniel Meyohas, Partner, Greybull Capital)
Greybull also oversaw Rileys Sports Bars, which fell into administration in September 2014.
The firm describe themselves as 'an entrepreneurial investment group, whose purpose is to improve businesses for all stakeholders'.
Their stated aim is to make companies successful by 'collaborating with management teams and employees and by investing our capital, time and expertise', with the hope of adding 'substantial value' to companies they take on.
Greybull invests wealth from two families - the Perlhagens, from Sweden, who made their fortune in pharmaceuticals, and Turkey's Meyohases.
Insolvency experts familiar with Greybull described its strategy and boss as sharp-elbowed, secretive and unafraid of publicity or taking big risks, the Times reported.
Pictured: Greybull Capital's office in London's Knightsbridge
In 2016 the secretive brothers behind Greybull warned that the rescue of British Steel might not work out.
On the first day of trading as British Steel it announced an investment package of £400million and revealed the business had been profitable for months.
But Greybull partner Marc Meyohas was cautious about the future, previously telling the Mail: 'We are the first to admit not every company we back will be a success – we don't hide from that fact.
'We conduct a difficult process investing in troubled assets which we try to turn around – we are not going to have a 100 per cent success rate. On the whole we try to get more right than wrong.'
The French-born brothers work with Swede Richard Perlhagen – the two families go back decades – and Greybull was set up to invest their combined fortunes.
Former Lehman Brothers banker Daniel Goldstein is the fourth partner, and it was previously reported that all are resident in the UK, working from Greybull's office in London's Knightsbridge.
Previous investments have included Plessey Semiconductors and retailer Game Group.
The Comet investment was seen as a dark period for Greybull, with some accusing it of profiting while workers were made redundant.
Meyohas said: 'We are sorry for what happened to Comet. It's annoying to be referred to as guys involved with that. We had a tiny holding and no board position, so had little control.'