After serving a short stint as Chairman of Irish state-owned bank ACCBank,[6] he returned to Britain on joining Barclays on 1 October 1999 as Group Chief Executive.

The scams were fairly simple – in a typical case, Barclays and an American bank would loan, say, an airline for the purchase of a jumbo jet.

This all came to a grinding halt when The Wall Street Journal published an exposé of the dodge in a front page, column one, article on 30 June 2006 by Carrick Mollenkamp, which ensured that Parliament, the Bank of England, and the UK Inland Revenue and the American Internal Revenue Service would see it and become aware of the scam, and the practice was subsequently outlawed, thus eliminating a major source of income for Barclays.

[9] When his retirement was suddenly announced, The Times of London reported that "The imminent departure of Mr Barrett will come as a shock to many in the City who expected him to stay on much longer as chairman".

He was made an Officer of the Order of Canada in 1994 for "fostering the advancement of women in the banking industry",[12] and has dual Irish and Canadian citizenship.