One trail that ties Trenport Investments to the Barclays is money. Its transactions are hard to make sense of unless Sir Frederick and Sir David were its owners. The other trail is human. The men who put Trenport together and ran it were not Bolsoms people, they were Barclays people. The common thread was a man called Stuart Brummer.

Brummer, who died of cancer in 1992 aged 53, had worked for M.D. Green, which audited various Barclays companies for decades. Brummer left the firm in 1970 to become the Barclays’ finance expert. He later set up a business-services company called Broomfield Secretarial Services, which handled corporate administration. For many years, Broomfield’s main clients were the Barclays.

If, as we believe, Trenport was really a Barclays company, it needed a different auditor from the rest of the family’s holdings, to help maintain the façade that it was independent. We believe that the Barclays delegated this task to Brummer, who chose a man called Michael Seal. Mr Seal then worked at an accounting firm called Goodman Jones. So far as we can tell, he had no connection at the time to either the Barclays or the Bolsoms.

Mr Seal, a partner and tax specialist, took on the Trenport account at Goodman Jones. He went on to become a member of the Barclays’ innermost circle of trusted advisers, serving as a director of over 120 of the Barclays’ British companies.

The Economist has found that Mr Seal was one of Brummer’s friends. Both lived in Southgate, a suburb of London. In 1970 Mr Seal was married at the Cockfosters and North Southgate Synagogue, where Brummer’s wife, Marilyn, worshipped. As a young married couple, Mr Seal and his wife were active in the JNF, a charity that supports Israel. Ms Seal was president in 1994-2008. Brummer was active in the JNF too, serving on its board, initially as its joint treasurer, in 1978-89. On Brummer’s death, the Seals posted their condolences in the Jewish Chronicle to “a very dear friend and colleague”.

It was a similar story with Joseph Frayman, the man who served alongside the Bolsoms as Trenport’s third director. He owned no shares in the company and, so far as we can tell, he also had no prior connections to either the Barclays or the Bolsoms.

However, Frayman, who had been London bureau chief for the New York Times, was Brummer’s father-in-law. He also worshipped at Cockfosters and North Southgate. Indeed, he wrote a history of the synagogue.

The Economist contacted Mrs Brummer and Mr Seal for comment. They offered no comment.

If Trenport had really belonged to the Bolsoms, you would have expected them to have ties to the people who helped administer it. Instead the connections run through Stuart Brummer to the Barclays. ■

Read the full investigation here.