George Osborne, the former UK chancellor, is joining the boutique UK advisory firm Robey Warshaw, dropping the eclectic set of jobs he has taken since leaving government to become a full-time mergers and acquisitions banker.

Mr Osborne will leave roles at London’s Evening Standard newspaper and US investment manager BlackRock and in April join as a partner at Robey Warshaw, which has advised on some of the largest deals in the UK since it launched in 2013.

The addition of Mr Osborne marks the first-time the firm has extended its partnership beyond its three founding members, Sir Simon Robey, Simon Warshaw and Philip Apostolides.

Mr Osborne said: “Robey Warshaw is the best of the best, advising great businesses on how to grow, and I’m proud to be joining this first-rate team.”

Mr Osborne follows a well-trodden trail of former politicians who go into the banking and advisory world to bring a network of powerful business and political connections cultivated over years of public service.

Others to do so include Eric Cantor, the former US Republican House majority leader who joined advisory firm Moelis & Co in 2014 as a managing director and Peter Orszag, who served in a cabinet role in Barack Obama’s administration and is now the chief executive of financial advisory at Lazard.

Mr Osborne will be expected to help with Robey Warshaw’s existing clients, which include FTSE 100 companies such as Centrica, Vodafone, BP and the London Stock Exchange Group, as well as identify new business.

Robey Warshaw said: “We believe that George will significantly enhance the advice we give to clients. He brings differentiated experience and expertise to our team from his leading roles in global finance over the past decade.”

Since joining forces in 2013, after the departures of Mr Robey and Mr Apostolides from Morgan Stanley and Mr Warshaw from UBS, the firm has been successful at winning high-profile M&A mandates on some of the largest deals in the UK market.

Most recently, it advised the LSE Group on its $27bn takeover of Refinitiv, the data provider that was carved out of Thomson Reuters in 2018 by private equity group Blackstone.

Robey Warshaw employs 13 staff and has made profits of £207m over the past seven years although its revenues dipped during a relatively quiet year for dealmaking in 2019.

Before joining, Mr Osborne will slim down an eclectic portfolio of jobs that he built since leaving government in 2016, which has ranged from finance and teaching to editing a newspaper.

While still an MP in 2017, he took a one-day-a-week advisory role at the asset manager BlackRock, earning £650,000 a year. Soon after the former chancellor took over as editor of the Evening Standard, a free London daily that has been hit particularly hard by the lockdown.

Mr Osborne was succeeded as editor by Emily Sheffield last year, but remained at the title owned by the Russian businessman Evgeny Lebedev as “editor-in-chief”. He is leaving the newspaper and BlackRock in March.

Mr Osborne will remain chair of the advisory board of Exor, the holding company through which Italy’s billionaire Agnelli family manages its interests.