The solicitor for former trader Tom Hayes has written to the Court of Appeal and Serious Fraud Office over concerns that one of the judges in Hayes' appeal had a ‘potential conflict of interest’ that was not disclosed to the parties.

Karen Todner, principal of Karen Todner Limited, said Mr Justice Bryan’s involvement in a previous EURIBOR appeal came to light only after the written judgment was published last week. Mr Justice Bryan sat on former Deutsche Bank trader Christian Bittar’s interlocutory appeal alongside two other judges.

Todner said she would have ‘definitely applied for a change of judge’ if she had been aware of the judge’s role in Bittar’s appeal.

Hayes, 44, was convicted in 2015 of multiple charges of conspiracy to defraud in relation to manipulations of the London Inter-Bank Offered Rate (LIBOR). He was sentenced to 14 years’ imprisonment, later reduced to 11 years. He has always maintained his innocence.

Following a three-day appeal hearing at the Royal Courts of Justice last month, Lord Justice Bean, Lord Justice Popplewell and Mr Justice Bryan upheld the convictions.

In her letter to the CoA, Todner questioned why Bryan’s ‘prior involvement in IBOR was not drawn to the attention of the parties’. She noted that the case had been referred to the CoA on the basis that the court might prefer the US courts' approach to that taken by the CoA in earlier cases. ‘Given that that was the basis of the referral, I am very concerned that one of the judges considering this appeal had in fact been party to one the previous decisions, the correctness of which was under challenge. Had I been aware of that fact, those concerns would have been raised with the court.’

In her letter to the SFO, she asked if the court had been made aware and ‘if not, why not?’.

Speaking to the Gazette, Todner said: 'Tom Hayes was entitled to an independent and impartial tribunal. Given Mr Justice Bryan’s previous involvement in one of the cases which we were seeking to overturn I’m not sure than an independent observer would agree that the tribunal was impartial or independent.

'If I had been aware of this beforehand, I would definitely have applied for a change of judge.'