The Children's Heart Federation charity has said it is "horrified" by the bill run up by the Royal Brompton Hospital, in its courtroom battle with another NHS body.
The hospital had challenged a consultation by the Joint Committee of Primary Care Trusts, which had proposed closing the children's heart unit at the Royal Brompton.
The charity has urged other hospitals not "to waste this level of money on further legal action".
More top news
Rail firms have repeated warnings to passengers travelling over the bank holiday weekend with major engineering work affecting several lines
A cyclist who ploughed into a mother-of-two has been cleared of manslaughter but convicted of "wanton and furious driving".
Women in Tower Hamlets can expect to live for 30 years in ill health, compared to just under 12 years for men in Enfield.