UPDATE 1-Britain's 'Big Four" grocers all lose market share - Kantar Worldpanel

(Adds table) LONDON, Oct 17 (Reuters) - Britain's "Big Four" supermarkets all lost market share in the 12 weeks to Oct. 8 despite growing sales as the march of the discount chains continued, Kantar Worldpanel said on Tuesday. Morrisons was the best performing of the four, with sales up 2.8 percent, Kantar said, followed by market leader Tesco up 2.1 percent. Sainsbury's sales were up 1.9 percent and Asda saw growth of 1.8 percent, it said. Discount chains Aldi and Lidl continu