Billionaire Sir Charles Dunstone has quit as chair of Royal Museums Greenwich over Culture Secretary Oliver Dowden's refusal to reappoint Aminul Hoque as a trustee.
Dowden's office has not offered an explanation as to why Hoque, a Bangladeshi-British academic who advocates decolonising the curriculum, was vetoed, saying only that "there is no automatic presumption of reappointment".
However, the move is being seen in the context of the Government's attempts to enforce its historical narratives on the UK's museums.
Dunstone, the founder of Carphone Warehouse, resigned as chair in Februrary immediately after warning Dowden he would do so if Hoque was not reinstated, The Financial Times reports.
Hoque said he was "shocked, disappointed and baffled" by the Culture Secretary's decision.