(190323) -- LONDON, March 23, 2019 (Xinhua) -- A placard is seen during the Put it to the People march in central London, Britain, on March 23, 2019. Hundreds of thousands of people on Saturday marched through central London calling for another referendum on Brexit as the country is caught by the Brexit impasse again. (Xinhua/Han Yan) BRITAIN-LONDON-BREXIT-REFERENDUM-MARCH PUBLICATIONxNOTxINxCHN