The mysterious crypto firm backed by Farage's biggest donor

In fact, the single biggest buyer of the precious metal last year was a company you've probably never heard of – a crypto firm called Tether.

The El Salvador-based company runs USDT, the world's biggest stablecoin, which is a form of crypto backed up by hard currency.

It serves as a conduit between riskier, volatile cryptocurrencies and the conventional finance system, essentially used as an offshore dollar.

Yet Tether bought more gold last year than anyone, according to European Central Bank data.

It keeps it stored in a James Bond-style Swiss former nuclear bunker, according to Tether's boss.

Tether says it also owns as much US Government debt as some G20 nation states, some $135bn (£101bn), which is more than South Korea.

It is a huge player, almost taking on the characteristics of a private central bank. Yet it employs just 200 people.

It is also, perhaps inadvertently, entangled in the questions around the funding of Nigel Farage's Reform party.

Last August, Harborne gave £9m in cash to Farage's Reform party – the biggest party donation in British history. He gave a further £3m to Reform in October and an additional £3m in January. All the donations were declared.

Harborne had given £5m directly to Farage, a previously undisclosed personal gift which was the subject of parliamentary investigations, before Farage resigned as an MP.

Farage and Harborne have both said there were no strings attached to the personal gift, nor to the political donations to Reform.

The Bank of England's governor Andrew Bailey recently confirmed that Farage raised the issue of cryptocurrency regulation and the related issue of central bank digital currencies with him in September last year.