This is incorrect. Whilst trustees do have a duty to maximise financial returns from the way they invest their charity’s assets, the Charity commission encourages charities to consider whether their investments are consistent with the charity’s aims.
The Charity Commission held a consultation with charities in 2021 to consider how clear its current guidance is and whether it should be expanded so the legality of responsible investing is clearer. Most recently a new high court judgement (Butler-Sloss & Ors v The Charity Commission for England and Wales & Anor  EWHC 974 (Ch) (29 April 2022), strengthened the case for charities excluding large parts of the investment market in relation to concerns around climate change. As stated by Bates Wells “Butler-Sloss provides comfort that there is no single ‘right’ investment policy for trustees to adopt. Trustees who apply themselves properly and reasonably to the task of balancing all relevant factors in formulating an investment policy which they believe in good faith to be in the best interests of the charity’s purposes should, in doing so, fulfil their legal duties.”