UK Stocks-Factors to watch on March 21

March 21 (Reuters) - Britain's FTSE 100 index is seen opening up 13 points on Wednesday, according to financial bookmakers. * CAMBRIDGE ANALYTICA: The suspended chief executive of UK-based political consultancy Cambridge Analytica claimed in secretly recorded video that his company played a decisive role in the 2016 election campaign of President Donald Trump, Channel 4 News reported on Tuesday. * BP: British oil major BP will drill its first deepwater exploration well at a blo