In a quiet cul-de-sac in London's exclusive Kensington area, there's an imposing Victorian town house that has an air of the Empire about it, even though its owners do not. The house which has eight bedrooms and six bathrooms spread over six floors, an elevator and a garden belongs to a Swiss family who, according to Tom Tangney, estate agent for realtor Knight Frank, make their money in finance. Tired of paying the upkeep on a place they hardly use, they've put it on the market for $18.5 million. And at that price, "I expect the buyer...