The respected chair of the House of Commons Treasury Select Committee, Andrew Tyrie, will stand down from Parliament at the general election.
The announcement leaves open one of the most powerful non-ministerial positions in Parliament, covering the economy, finance and also elements of the Brexit process.
The Conservative MP for Chichester since 1997 said that he had made the decision "after very careful thought" adding that he remains "deeply committed to public service".
Mr Tyrie, 60, added: "I am determined, and hopefully young enough, to contribute in other ways in the years ahead".
Under Mr Tyrie's leadership since 2010 the TSC has been a source of often forensic scrutiny of senior politicians, civil servants and financiers.
As chair, he clashed frequently with the former Governor of the Bank of England, Mervyn King, over issues of governance at the central bank and had regular tussles with the former Chancellor, George Osborne, over the disclosure of Treasury analyses.
Charlotte Hogg, a deputy governor of the Bank of England, resigned in March after it was uncovered by the Committee that she had failed to disclose to the Bank that her brother was employed by Barclays.
Mr Tyrie also chaired the Parliamentary Commission on Banking Standards, which reported in 2013.
Last September he wrote a hard-hitting report for the Open Europe think tank on "giving meaning to Brexit" in which he said that leaving the EU without a trade deal and trading on World Trade Organisation rules would "amount to shock therapy" for the economy.
He also founded an All-Party Parliamentary Group on Extraordinary Rendition.
Mr Tyrie, formerly an economist at the European Bank for Reconstruction and Development, retained the safe seat of Chichester in 2015 with a 24,413 majority over his Labour opponent.
The Treasury Select Committee chair, along with a number of others, is elected by MPs at the start of a new Parliament under an Alternative Vote system.
But Mr Tyrie was re-elected unopposed in 2015, reflecting his standing among fellow Parliamentarians.
Andrew Bailey, the head of the Financial Conduct Authority, paid tribute to Mr Tyrie, saying he has "played a major role in enhancing the accountability of economic and financial policy at a time of great change."
