London ( CNN ) -- Former British Prime Minister Margaret Thatcher `` has undergone surgery to remove a growth in her bladder '' and is currently recovering in the hospital , her spokeswoman , Gillian Penrose , said Friday . Thatcher , 87 , is doing `` absolutely fine '' after the operation , her spokeswoman said . She was admitted to the hospital Thursday and is expected to be kept overnight . Britain 's only female prime minister , Thatcher served from 1979 to 1990 as leader of the Conservative Party . She was called the `` Iron Lady '' for her personal and political toughness . She enjoyed a close friendship and working relationship with the late U.S. President Ronald Reagan , with whom she shared similar conservative views . Thatcher retired from public life after a stroke in 2002 and suffered several strokes after that . She makes few public appearances . She missed a reception in honor of her 85th birthday hosted by Prime Minister David Cameron in October 2010 and skipped the unveiling of a statue of Reagan in London in July last year . Per Nyberg reported from London . Melissa Gray reported from Atlanta .
Thatcher 's spokeswoman says she had a tube in her bladder removed . She is expected to be kept in the hospital overnight and is ` ` absolutely fine '' Thatcher , however , was Britain 's only female prime minister and held office from 1979 to 1990 .