Muller yoghurt and Flora margarine enjoyed the biggest gains in Britain's top 20 grocery brand rankings while two Procter & Gamble products were among the big losers, market researcher ACNielsen said on Wednesday. Annual sales of Muller pot desserts rose 21 per cent while Flora spreads increased 20 per cent in rankings in which there were no changes among Britain's seven most popular groceries. Germany's privately owned Muller continued to strengthen its number one spot in the UK yoghurt market against Northern Foods' Eden Vale Ski and Uniq's St Ivel Shape brands. Unilever's Plc/NV Flora brand was helped by the performance of its Flora pro.activ cholesterol-lowering spread. "This year's 'climbers' are dominated by brands which have demonstrated continuous innovation," said Greg McDonald, client service manager of ACNielsen. But there was no change within the top seven UK grocery brands led by Coca-Cola with annual sales of 491.4 million pounds, followed by PepsiCo's Walkers crisps, Nestle's Nescafe instant coffee, Muller and Unilever's Persil washing detergent. "Many of these brands have filled the nation's cupboards, fridges and freezers for decades and the survey illustrates the top brands longevity, and just how hard a task it is for new brands to make their mark on the Top 100,"said Stephen Foster, editor of trade magazine Checkout, which uses the Nielsen data for UK grocery market analysis. Big losers within the top 20 were Procter & Gamble brands Ariel washing detergent and Pampers disposable nappies. Ariel's sales fell 13 percent as it slid to 12th from the number eight position, while the Pampers' turnover dipped 10 per cent and its ranking slipped to 14th from ninth.All the data in the Nielsen report is based on annual sales in the year to mid-August. ACNielsen is part of Dutch media group VNU NV, and claims to be the world's leading market research firm.