Susan and Christopher Edwards were both found guilty of the murder of her parents at Nottingham Crown Court today.
The pair buried William and Patricia Wycherley in their own back garden, then pretended they were alive in order to swindle hundreds of thousands of pounds.
Their plan unravelled when an official wanted to meet William Wycherley on what would have been his 100th birthday.
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Her Majesty toured the show for 45 minutes.
M&S chief executive, Steve Rowe, has decided to take a more aggressive approach.