A wealthy businessman was suffering from delusions when he left the Conservative Party more than £8 million in his will, a High Court judge ruled.
Branislav Kostic lacked "testamentary capacity" when he cancelled an earlier will in which he had left everything to his son, Zoran, his only child, Mr Justice Henderson said.
Ruling on Zoran's legal challenge to wills made in favour of the Conservative Party Association in 1988 and 1989, the judge upheld a 1974 will, made at a time when nobody disputed he had full capacity, under which Zoran was the sole beneficiary.
Mr Justice Henderson said the old man suffered from a serious and untreated mental illness from at least mid-1984 onwards.
The central feature of his delusions was the belief that there was an international conspiracy of dark forces against him in which his wife, mother and sister, together with many others, were implicated.
The judge held that Mr Kostic was unable to form a proper appreciation of Zoran's claims on his estate.
His natural affection for his son had been poisoned or distorted by his delusions to such an extent that he was "wholly unable to dispose of his property in the way he would have done if of sound mind".
His decisions to leave the whole of his estate to the Conservatives and to request them to establish a foundation in London in memory of his late father, Milan Kostic, to promote what he called the Christian Democratic values of love, truth and freedom "were themselves in part the product of his delusions", the judge said.
