Sheikh Hamad bin Jaber Al Thani was the key figure behind investments in the UK while he was prime minister of Qatar and head of the sovereign wealth fund.
The Qataris were involved in deals to buy stakes in key London landmarks and institutions including hotels, upmarket property and the upmarket department store, Harrods.
Qatar is part owner of Heathrow airport and at the time of the capital raising operation in 2008 was expressing interest in investing in Gatwick, the capital’s second main airport, emails showed.
He owns a flat in a Qatari-backed exclusive development overlooking Hyde Park in central London, part of an estimated £30 billion of Qatari investments in the UK.
Of the most controversial investment, the purchase of a stake in Barclays, he told the UK's Financial Times newspaper in 2016 that he had no regrets.
“No, I think it’s a good investment. I regret the noise. We thought we had helped the British economy at a bad time and that someone would thank us for it,” he said.
He stepped down as both prime minister and running the wealth fund in 2013.
Mr Jenkins, 64, was the key player in securing Qatari funds and was recommended for a £25 million bonus for his work on the deals.
He first met Sheikh Hamad in 2007 and was the “gatekeeper” between the bank’s board and the Qataris as they sought investment during the 2008 financial crisis.
He has been known as Britain’s best-paid banker, earning bonuses of £36 million in 2007 and £19 million in 2009.
The court heard how he worked 80-90 hour weeks for the bank and suffered a heart attack during the tumultuous events of 2008, but returned to work weeks later.
He held some £60 million of stock in the bank and when he left in 2009, he had amassed a £120 million fortune, according to the Sunday Times Rich List.
John Varley was chief executive of Barclays from 2004 to 2010 covering the most turbulent years in British and global banking since the 1930s. His strategy to secure £11 billion in funding from investors rather than rely on a taxpayer bailout meant it was able to keep its independence from the government, unlike many of its rivals.
During his time in charge, he also secured the investment banking arm of Lehman Brothers in North America, which was stricken by the subprime mortgage crisis.
He played a central role in meeting and negotiating with the Qataris and became the highest-ranking banker to be charged over the fallout from the 2008 crisis. He was charged in 2017 but the case against him was thrown out because of insufficient evidence.
Bob Diamond, the man who succeeded John Varley as chief executive, was famously described as the “unacceptable face of banking” by Lord Mandelson, a senior minister in the government of Tony Blair.
The comment was prompted by claims that he had earned tens of millions of pounds for his work at Barclays.
At the time of the capital raising, he headed the Barclays Capital division and was involved in efforts to woo Gulf-based investors. He was interviewed under caution by SFO investigators but never charged with a criminal offence.
He became the chief executive in January 2011 but was forced to quit the following year after the bank was fined a record sum for trying to manipulate inter-bank lending rates.