Hargreaves Lansdown earned more than £40m in client fees on the now-suspended Woodford Equity Income Fund since its launch in 2014, with more than £20m generated in the last two years despite the fund’s increasingly poor performance.

Responding to a letter from Treasury select committee chair Nicky Morgan, Hargreaves Lansdown said platform fees on client investments in Neil Woodford’s flagship fund had totalled £41.1m to the end of April.

Hargreaves charges a flat 0.45pc fee on all fund investments, regardless of the type of fund or its manager.

The Telegraph understands that the Woodford Equity Income fund had stopped being a "top 10 earner" for Hargreaves Lansdown as performance at the fund started to slide.

In the letter, Hargreaves said it first identified an increase in the proportion of small and unquoted assets in the Woodford Equity Income fund in November 2017.

“We met with the fund manager that month and urged him to address the issue. The manager committed to us that he would make no new investments into unquoted businesses from that point,” the firm said.

Hargreaves said it then insisted on regular meetings to track how Mr Woodford was rebalancing the portfolio.