UK Stocks-Factors to watch on Nov 28

Nov 28 (Reuters) - Britain's FTSE 100 index is seen opening 3 points higher at 7,387.2 on Tuesday, according to financial bookmakers. * BHP BILLITON: BHP Billiton Ltd said on Tuesday it is looking at an expansion at its Olympic Dam copper mine in south Australia, which could sharply lift annual production capacity from the project. * BRITAIN-PROPERTY: The number of new office developments in London is falling as higher construction costs and uncertainty over Brexit lead bui