Heronbridge, which has £800 million of assets under management, will run the mandate in accordance with its Heronbridge UK Equity strategy.

Heronbridge employs a long-only equity approach, covering both large and smaller capitalised companies and also uses a benchmark-unaware stock picking strategy which focuses on 40 UK-listed companies, the firm said in a statement.

The mandate will represent approximately 5 per cent of the Witan Investment Trust portfolio which was previously managed by NewSmith Asset Management. 

“The appointment of Heronbridge is a continuation of our move to invest with specialist managers who are innovative and have differentiated and high-conviction approaches towards creating value through stock picking and portfolio construction. At the same time, we would like to thank NewSmith Asset Management for their stewardship of the company’s assets over the past three years," said Andrew Bell, chief executive of Witan.

Witan manages £1.2 billion on behalf of over 31,000 investors, as of 31 December 2012, and is a member of the FTSE 250 index.

Heronbridge currently manages £811 million, as of 31 May 2013, for institutional, charity and high net worth clients in the UK, the US and elsewhere.