However, the Tories argued that there were rational reasons why Mr Kostic left his son out of his will.
The court heard that Mr Kostic had rejected his family, believing they were conspiring against him.
He made the will after saying Margaret Thatcher was "the greatest leader of the free world in history" and that she would save the world from the "satanic monsters and freaks".
Lawyers for the Conservative Party Association earlier told Mr Justice Henderson that Mr Kostic and his son had become estranged and that he was unhappy with his son's career choices.
The party's barrister Andrew Simmonds QC said there was also Mr Kostic's "great and long-standing affection for the Conservative Party and his admiration for Mrs Thatcher".
Tories go on about family values and the Government not stealing peoples money, but their quite happy to join in a familial dispute, spread some dirt and try to take an insane guys money.
Then again, to leave the Tory party some money, you'd need to be a little crazy.