Shrewd investment

Marcus bought well when young. The well-paid electronics boffin invested in property at the end of the 1960s, just before Britain's huge housing boom. His detached property bordering Hampstead and Finchley Road had shot up in price, now commanding well over £2million.

When he married Grace, she shared his house, although his dark character must have shown through back then when, unusually for the times, he insisted she relinquish any future claims via a prenuptial agreement.

Grace, besotted then with the man she thought he was, went along with it.

Her surviving brother saw an opportunity to reverse this....