Jonathan Nuttall, 50, who was suspected of involvement in an international money laundering ring, hatched the plan after becoming upset at the prospect of losing his stately home, Embley Manor in Romsey, Hampshire.

He used his driver, Michael Sode, 58, as a middleman to recruit former Royal Marine Michael Broddle, 47, to carry out research and reconnaissance on lawyers Andrew Sutcliffe KC and Anne Jeavons.

The three men were convicted of conspiring to plant two smoke devices at Gray's Inn in London, the heart of the English legal district, on 14 September 2021 after a four-month trial.

Nuttall was jailed for eight years and two months on Friday, while Sode and Broddle were handed sentences of six and a half years and seven years respectively.

Judge Simon Mayo KC said: "In my judgment, this was a malicious, bold and extremely serious attack on those involved in the administration of justice.

"Your agreed purpose was to undermine the administration of justice.

"I am entirely satisfied that you intended serious harm to be occasioned by your agreed course of conduct.

"It is patently clear that the leaving of those devices would inevitably cause widespread alarm and disruption."

The Old Bailey heard he came up with the bomb plot after being pursued by the NCA over the seizure of assets worth £1.4m.

He had a flat near Sloane Square in west London and a chauffeur-driven Rolls-Royce but neither was owned by him, while his wife, Amanda Nuttall, who had won a lottery jackpot of £2.4m, was named on the NCA legal papers, jurors were told.

Giving evidence, Nuttall spoke of his wife's "extraordinarily good fortune" but said "regrettably" most of her winnings went to pay off his brother's gambling debts.

Smoke grenade bomb plot

One device, left near a bench, was spotted by a porter and later found to be "potentially viable" as it contained a smoke grenade, while another smoke grenade was let off with the second non-viable device with the intent to cause "maximum alarm", the court heard.

Mr Sutcliffe told the jury he was "shocked" and "dumbfounded" when he found out what had happened.

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Broddle, who was paid around £7,000 via Sode, was arrested two days after the devices were planted and police seized fireworks, gas canisters, a hat and wig and rubber face masks from his home.

Before being arrested, Nuttall hid a mobile phone inside an office chair and Sode threw his out of a window, the jury was told.

Sode denied wrongdoing and claimed he was involved in recovering debts from clients of an escort agency business, while Broddle took responsibility for planting the devices but declined to name who he was working for.

He told jurors he would do anything for money but insisted he "had no problem with Mr Sutcliffe" and was simply "acting on instruction".

Nuttall, and Sode, of Deptford, southeast London, were found guilty of two charges of conspiring with Broddle, from Hounslow, west London, to place an article with intent on or before 14 September 2021.

The three men were convicted of conspiring to transfer criminal property, while Nuttall was also found guilty of two charges of failing to comply with a notice and Sode was found guilty of one similar charge.