Mr Jenkins said that Mr Lucas and lawyer Mr Harding felt it was the “right time for them, personally and professionally, to pass the baton on in their respective roles”.
He added: “Chris and Mark both expressed to me late last year that they were considering stepping down from their roles at Barclays.
“The rationale which each shared with me was consistent and, typically, grounded in wanting to do what is best for the bank. Their decision to retire was theirs alone.”
Mr Lucas could stay at the bank for up to a year as Barclays hunts for a replacement. Barclays has appointed headhunters to lead the search for a new finance director and is likely to turn to a candidate from outside the bank to replace Mr Lucas.
Mr Lucas has been working at Barclays for the second time in his career, after being employed at the bank as a global relationship partner between 1999 and 2004. He also worked as UK head of financial services and global head of banking and capital markets at PricewaterhouseCoopers.
Mr Lucas is paid an annual salary of £800,000 at Barclays and earned almost £4m in each of the last two years, including bonuses and deferred share awards. Barclays is yet to determine whether he will receive compensation upon leaving the bank.
On top of the departure of Mr Lucas, Barclays will be in the spotlight on Tuesday when Mr Jenkins and the bank’s chairman, Sir David Walker, appear in front of the Parliamentary Commission on Banking Standards.
The bosses of HSBC and Lloyds Banking Group are also due to appear in front of the committee.
Meanwhile, Royal Bank of Scotland could this week face criminal charges and be handed a £500m fine for its role in the Libor scandal. The bank is thought to be under pressure from the Government to pay the fine with cash from its bonus pot to ensure taxpayers do not suffer.