Former foreign secretary Lord Hague is to join Wall Street giant Citi as the UK gears up its Brexit strategy ahead of talks with the European Union. William Hague is to join Citi as an advisor at the US bank, providing insight to the lender's clients, it was announced on Tuesday (17 January 2017).

Citi said: "We're delighted Lord Hague will be working with Citi as an advisor, providing his unique perspective to our clients. Lord Hague's experience on the global stage and his understanding of the forces shaping the world will be a key asset for Citi".

The move comes as Britain's Prime Minister Theresa May said in a keynote Brexit speech on Tuesday that the UK "cannot possibly" remain within the European single market, as staying in it would mean "not leaving the EU at all".

The UK is expected to open Brexit negotiations with the EU by the end of March.

Hague's appointment follows Lord King, the former governor of the Bank of England, who also joined Citi as senior adviser in July last year.

Hague, who also served as the leader of the Conservative Party in Britain, quit frontline politics at the 2015 General Election, but voiced support for Britain to stay inside the European Union. Citi, which employs around 9,000 people in Britain, was a substantial donor to the campaign to stay in the EU.

Banks have appointed numerous advisers who in the past sat at the top table of global politics and central banking. They include former leaders of Britain, Mexico, Australia and Sweden, top European policymakers, and former central bank governors from the US and Europe.

Former European Commission president Jose Manuel Barroso joined Goldman Sachs in July as an adviser and non-executive chairman of its international business, which sparked controversy and an EU ethics investigation which subsequently cleared him of any conflicts.

JPMorgan hired former British prime minister Tony Blair in 2008 to advise on strategic and political issues, and it also has former Italian finance minister Vittorio Grilli and ex-Israel central bank boss Jacob Frenkel as vice-chairmen.