Marlborough Special Situations has outperformed all of its rival funds since Isas launched in 1999.
Stock-picking veteran Giles Hargreave has run the £1.5bn fund since 1998, and was joined by co-manager Eustace Santa Barbara in 2014.
During Mr Hargreave’s tenure, the fund, which invests in small UK companies, has delivered a total return of more than 2,900pc, compared with 509pc for the average peer, and 168pc for the FTSE All Share index.
Telegraph Money spoke to the managers about what they are buying and why they still own a stock that has fallen 92pc.
How do you invest the fund?
GH: I can’t tell you what is going to happen to markets any more than anyone else. There is all sorts of potential...