Graham Birch, head of BlackRock's Natural Resources team, has decided not to return to the company following his nine-month sabbatical.
Birch's top-performing BlackRock Gold and General fund and World Mining trust will be handed over to Evy Hambro, who has successfully managed the vehicles throughout Birch's period of leave.
"It has been an honour working with Graham Birch, He has made a huge contribution to the team and we wish him all the very best for the future," Hambro says.
"The natural resources team is well set for the future, with great depth of experience and resource.
"We have traditionally maintained strength in depth as demonstrated by the strong performance achieved for investors since Julian Baring left us in 1998."
The BlackRock Gold and General fund was the top UK unit trust the last decade, returning 684% to investors.
Savers losing an average of £91,000
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