The eye-watering prices achieved for masterpieces in the past years have encouraged ever more collectors to sell, experts say, and the expanding class of buyers is helping keep demand strong.

"When you get very significant prices achieved by global buying, people will know that not only are they getting the highest price but they are selling to the broadest possible audience," Jussi Pylkkanen, president of Christie's Europe, told Reuters by telephone on Friday. "That creates its own impetus."

A growing class of the super-wealthy in emerging markets, particularly China, Russia and the Middle East, have been increasing their buying power in a sector typically dominated by US and European collectors.

Pylkkanen said that the Bacon piece sold on Thursday would probably not have come to market had it not been for the record-setting triptych last November. "That gives confidence to American and European buyers," Pylkkanen said.

"London and America, which (are) the stock exchanges of the art market, (are) able to offer these pieces to a much broader audience."

Thursday's sale followed that held by Christie's rival Sotheby's a day earlier which saw buyers parting with 88 million pounds ($146 million).

Auction officials have pointed to London's position as a financial centre and its attractive real estate market as reasons for buyers flocking to the British capital.

"London is a centre of art production and private and institutional collecting, supported by a network of creative and financial industries, and its global location physically as well as ideologically positions it well for the exchange of art in a secondary market," said Dida Tait, Head of Development & External Relations, at the Contemporary Art Society.