GSK’s chief executive, Emma Walmsley, has come under pressure from a second activist hedge fund, Bluebell Capital Partners, which has taken a stake in the drugmaker to push for change at the top, including demanding that she reapply for her job. The London-based Bluebell Capital Partners has joined the US hedge fund Elliott Management on the pharmaceutical giant’s shareholder roster, with a stake reported to be worth £10m. With £100m assets under management, Bluebell is a much smaller firm than Elliott, which snapped up an undisclosed stake in April. But the two-year-old UK firm has already made waves by unseating the chief executive of the French consumer goods group Danone earlier this year. In a letter to GSK’s chair, Sir Jonathan Symonds, on Wednesday, Bluebell called on the company to appoint more directors with scientific experience to its board, and to run a “thorough and robust process” to find a leader for the drugs and vaccines business, following the planned spin-off of the consumer health division next summer. GSK put out a firm rebuttal, saying that Walmsley would lead the pharmaceuticals and vaccines company after the split. Marco Taricco and Giuseppe Bivona, the chief investment officers at Bluebell, said GSK’s financial performance had been disappointing during the last few years, and argued that Walmsley had less industry experience than other pharma bosses. “New GSK deserves the right leadership, able to review and potentially adjust the strategy outlined in June, ensure high quality execution, and rebuild trust with employees, customers, suppliers, and shareholders,” they wrote. They added that if Walmsley was reappointed as the best person to lead the drugmaker by a board with more scientific experience, this would give her “renewed credibility both internally and externally”. Bluebell also demanded that GSK adopt a “proactive” stance to find a buyer for the consumer health business. Taricco told the Guardian that GSK’s chairman had responded to the letter and promised to meet with Bluebell shortly. “We want this to be very constructive. It’s never anything personal. We go by facts and data.” He rejected any suggestion that Bluebell was acting in partnership with Elliott. “We are totally independent. We have been shareholders in GSK for several months.” A GSK spokesperson said: “The board is confident that we have the right strategy and the right team. Under Emma’s leadership, the board expects the team to deliver the new ambitions set out at our investor update in June, through separation and in the years beyond.” GSK said it had held more than 500 meetings with its shareholders so far this year. “They have expressed widespread and strong support for our plans to deliver a step-change in growth and performance, and given clear direction to focus on execution.” The drugmaker will hold a meeting in partnership with the independent group Investor Forum on 7 October, at which its chairman and senior independent director Vindi Banga will take questions from the 50 top investors.