As if the loss of sovereignty over Hong Kong earlier this year wasn't bad enough, the sun is about to set on another legacy of the British empire.

The home of the cuppa' is bidding farewell to London's weekly tea auctions after more than 160 years, as on-line trading and international competition gather steam.

Screen-based trading has undermined the commercial viability of the auction houses. That has been compounded by the success of regional markets in once distant corners of the empire such as those in Mombasa, Kenya, and Calcutta, India.