The man leading a probe into the culture of Barclays flew to the US this week to take evidence from Bob Diamond, the bank's former chief executive, I understand.
Anthony Salz, who was appointed in July following Barclays' £290m fine for attempting to rig the Libor interbank borrowing rate, is interviewing dozens of witnesses as part of his inquiry.
Mr Diamond is understood to have met with Mr Salz in the last 24 hours to provide input to the review, which is examining all areas of Barclays' business practices and culture.
The inquiry will lead to the establishment of a new code of conduct for Barclays staff, according to the bank.
As part of Mr Diamond's severance deal, the former Barclays chief received a package worth about £2m in return for agreeing to provide support for the transition to his successor, Antony Jenkins.
Mr Diamond is not expected to be called as a witness to give evidence to the Parliamentary Commission on Banking Standards, which is chaired by the Conservative MP Andrew Tyrie.
During his brief time as Barclays' chief executive, Mr Diamond endured several heated encounters with Mr Tyrie in his capacity as chair of the Treasury Select Committee, including one infamous remark that "the time for [bankers'] remorse needs to be over".
Barclays and a spokesman for Mr Diamond declined to comment.