Freshfields Bruckhaus Deringer has recruited the UK's former European commissioner for financial services Jonathan Hill as a senior adviser, following his resignation in the wake of the Brexit vote last year.

Hill – who was appointed as Commissioner for Financial Stability, Financial Services and Capital Markets Union by former Prime Minister David Cameron in 2014 – quit his role on 25 June last year, two days after the UK voted to leave the European Union.

In his resignation letter, Hill said that he was "very disappointed about the result of the referendum", and that he "had hoped that Britain would want to play a role in arguing for an outward-looking, flexible, competitive, free trade Europe.

"I came to Brussels as someone who had campaigned against Britain joining the euro and who was sceptical about Europe," he said. "I will leave it certain that, despite its frustrations, our membership was good for our place in the world and good for our economy. But what is done cannot be undone."

In his new role at Freshfields, which will be part-time, Hill will advise the firm and its clients on Brexit-related matters.

The European Commission was required to approve his appointment at Freshfields, as he is subject to a "cooling-off period" of 18 months after stepping down, during which he must notify the Commission of any plans to take up a new position.

To avoid conflicts of interest, he will be restricted from: advising any of Freshfields' financial services clients; advising Freshfields or its clients on issues related to the financial services sector; or lobbying on behalf of Freshfields or its clients with the Commission on any financial services-related matters.

The news comes on the day that Prime Minister Theresa May has triggered Article 50 of the Lisbon Treaty, starting the two-year countdown to the UK's exit from the EU.

Hill was made a life peer in 2010 as Baron Hill of Oareford, taking up a role as Conservative Parliamentary Under-Secretary of State for Schools in the Department for Education. He was then appointed as Leader of the House of Lords in 2013.

Freshfields senior partner Edward Braham said: "Jonathan brings outstanding experience and skill from a diverse and extensive career that is valuable both to our clients and to our firm. We have shown significant strength as a firm with regards to Brexit-related issues, and Jonathan's contributions, while respecting his obligations, can only enhance our reputation and our efforts."

The Commission has also approved his appointment as one of six independent national directors of The Times Newspapers. According to the House of Lords register for interests, he has given speaking engagements for Simmons & Simmons and Irish law firm Mathesons in recent months.

Many top law firms have been boosting their Brexit-related capabilities in the wake of the last year's referendum.

DLA Piper announced today (29 March) that it has appointed Paul Hardy, ex-EU legal adviser to the House of Lords, as a legal director and lead Brexit specialist. Hardy, who was called to the Bar in 1992 and was a legal adviser in the European Commission from 2004 to 2008, will join the firm next month. He was appointed counsel for European legislation in 2009 in the House of Commons and EU legal adviser to the House of Lords in 2014.

In January Linklaters signed up Cambridge University international law expert Lorand Bartels as a part-time senior counsel, while last December, Kings College reader in international economic law Federico Ortino joined Clifford Chance on a part-time basis and senior European Commission lawyer Eric White joined Herbert Smith Freehills as a consultant.

Last September, Freshfields Bruckhaus Deringer recruited former HM Treasury lawyer Anthony Parry as a full-time consultant, while Linklaters has also been working with former Conservative foreign secretary William Hague, who chairs the firm's international advisory group.