Former British prime minister Margaret Thatcher was said to be feeling 'a lot brighter' in hospital Saturday as she recovers from a bout of flu. The 1980s premier, who has been in frail health for a number of years, was admitted to a west London hospital for tests on Tuesday. 'She is a lot brighter. She is sitting up in a chair in her own room now,' a spokesman for Thatcher said. 'I think we are still going to be here for several days yet just to make sure.' Thatcher was forced to miss a planned 85th birthday party at Downing Street on October 14 due to her illness. Known as the 'Iron Lady', Thatcher was the longest-serving British prime minister of the 20th century and the only woman to serve as premier. 