Dechert’s former head of white-collar crime Neil Gerrard was involved in ‘the most grotesque perjury’ – representing ‘in all likelihood the most serious fraud on the court in English legal history’, the High Court has heard.

Aviation tycoon Farhad Azima’s lawyers have accused Gerrard and his former client Ras Al Khaimah Investment Authority (RAKIA) of a ‘conspiracy to defraud the court’ during a multi-million pound fraud claim brought against Azima. But Azima now intends to seek permission to bring an additional counterclaim against RAKIA to set aside the High Court’s judgment against him in that case ‘as having been procured by fraud’, the court heard on Friday.

RAKIA, Gerrard and Dechert are alleged to have been involved in the hacking and publication of Azima’s emails ahead of the trial, after which Azima was found to have engaged in ‘seriously fraudulent conduct’ against RAKIA. Azima's counterclaim was then dismissed.

Azima’s application for permission to appeal the fraud judgment was dismissed – and rejected by the Supreme Court in April – but his counterclaim was revived by the Court of Appeal, which found there were grounds to consider whether RAKIA’s defence was ‘dishonestly advanced’.

The High Court has since heard claims that Gerrard put key witnesses through ‘perjury school’ at a Swiss hotel ahead of the trial of RAKIA’s action against Azima to rehearse a false account about the ‘innocent discovery’ of his emails online.

Gerrard and Dechert ‘strenuously' deny any part in the hacking or dissemination of Azima’s data and stated in their joint written defence – filed in April, before Gerrard was dropped by solicitors acting for him and Dechert – that Gerrard ‘did not conduct a “mock trial” as alleged or at all’.

Last week, RAKIA abandoned its defence to the counterclaim, citing Gerrard’s ‘dishonest and unscrupulous’ conduct and the findings in a case brought by another former client, Eurasian Natural Resources Corporation (ENRC).

The former Metropolitan Police officer, 67, leaked ENRC’s confidential information to three newspapers and the Serious Fraud Office because he was ‘obsessed with making money’ and ‘plainly lied’ on oath, Mr Justice Waksman said last month.

RAKIA – which says it ‘did not authorise or procure any hacking of Mr Azima’s data and does not know who carried out this hacking’ – has offered to settle Azima’s case for $1m (£815,000) plus costs and ‘decided to take no further part in these proceedings’.

But Azima’s lawyers described the offer as ‘derisory’ and want permission to bring an additional counterclaim against RAKIA to overturn the High Court’s judgment ‘as having been procured by fraud’.

‘RAKIA’s claims – and the entire case it ran to substantiate them at trial – were obviously fraudulent in view of its targeting of Mr Azima including through hacking and its knowledge of the material stolen through its illegal hacking campaign,’ Tim Lord QC argued in written submissions.

He added that the ‘conspiracy to defraud the court’ at the original trial ‘may be seen to be in all likelihood the most serious fraud on the court in English legal history’.

Dominic Holden, Azima’s solicitor at Burlingtons, said in a witness statement that RAKIA’s witnesses – including Gerrard and the ruler of Ras Al Khaimah – ‘seem to have committed contempt of court and/or perjury’.

Mr Justice Michael Green said Azima’s application to bring an additional counterclaim will be considered at a later hearing, possibly a case management conference in October.