A former senior lawyer at the Serious Fraud Office has claimed he was the subject of an ‘unlawful plot’ to get him fired for allegedly swearing at an FBI agent in a pub in 2016.

Tom Martin, a former case controller at the anti-fraud agency, told the employment tribunal in London that there was a ‘conspiracy’ between the US Department of Justice and senior members of the SFO to remove him from a high-profile corruption investigation into Monaco-based oil and gas consultancy Unaoil.

Martin, who is suing the SFO for unfair dismissal, was sacked in 2018, after allegedly using expletives and calling an FBI agent a ‘spy’ and/or a ‘quisling’ in an altercation in a pub.

According to closing submissions filed with the tribunal, the SFO conducted an inadequate investigation into matters on which Martin relied in his defence; had an ulterior motive for his removal; and displayed procedural unfairness.

Jason Galbraith-Marten QC, of Cloisters Chambers, told the tribunal that Martin previously had a clean disciplinary record and had been rated outstanding in each of the four years he spent with the SFO.

He added that prosecution lawyers and prosecutors ‘commonly communicate in [a] robust and plain manner’.

In its closing submissions, the SFO said Martin’s case was a ‘a straightforward gross misconduct fair dismissal’ and that the agency held the ‘honest and genuine belief in his guilt of gross misconduct which was in the range of reasonable responses and chose to dismiss him’.

It added that Martin ‘exaggerated his own importance’ and was simply ‘a cog in the wheel under the management of others’.

Judgment was reserved.