A Canadian multi-millionaire wants to triple the size of his mansion by adding three stories below ground, drawing the wrath of many residents in his posh London, England, neighbourhood, the Daily Mail reports.

In 2000, David Graham — who pocketed much of his worth after selling his cable TV business — bought a two-storey home in London's Knightsbridge neighbourhood. Now, Graham wants construction workers to dig more than 15 metres underground to build a massive extension.

According to planning proposals, the three-storey addition will include a 14-metre swimming pool, spa, ballroom, gym, staff quarters and a three-car garage. When completed, the house will boast 15 bedrooms, seven bathrooms and 20 toilets. After construction, it could be worth more than $142 million.

'It's just absolute greed'

However, his wealthy Knightsbridge neighbours, which include novelist Edna O’Brien and the Duchess of St Albans Gillian Beauclerk, are not happy with the proposal.

"These plans are absolutely monstrous and unnecessary. It's just absolute greed. No one needs that much space," the duchess told the Daily Mail.

The community should not have to suffer just so one man can indulge his fantasy, said a member of a nearby residents' association.

Graham, 75, stated in his application for expansion that he attempted to find a bigger property in the area for his family, but was unsuccessful. As an alternative, he wishes to expand his current property.

He said the expansion is necessary to provide for his "family’s needs as required by today’s contemporary living." Graham was previously married to Barbara Amiel, Conrad Black's wife.