Margaret Thatcher was not among the 16 women politicians named
Harriet Harman's officials have been forced to change a government fact sheet celebrating "women in power" which did not name Margaret Thatcher.
The Equalities Office "milestones" list names Labour politicians like Diane Abbott and Baroness Scotland.
But it did not mention Lady Thatcher by name, saying only: "1979: UK's first woman prime minister".
An Equalities Office spokesman said: "We have acknowledged the oversight and have taken steps to amend it."
He said Lady Thatcher's name would be added to the document, one of a number of fact sheets produced by officials in Ms Harman's Government Equalities Office celebrating the achievements of women and ethnic minorities.
Asked whether the "Women in Power: Milestones" list, which is on the Equalities Office website, was an example of party political bias in a government document, he said: "There really isn't much more to say about this."
The fact sheet begins in 1907 with "First woman councillor elected in Britain - Reina Emily Lawrence" through to modern firsts for women such as Labour peer Baroness Uddin becoming the "first Muslim woman in the House of Lords" in 1998 and Labour's Baroness Amos becoming the first black woman Cabinet member in 2003.
In addition to being the first female prime minister, Lady Thatcher was also the first woman to lead a British political party when she took over the Conservatives in 1975 and the 20th century's longest serving prime minister, winning three general elections.
Here is the full un-amended list of "women in power" that was published on the government website:
Women in Power: Milestones
1907 First woman councillor elected in Britain - Reina Emily Lawrence
1918 Women over 30 have the right to vote
1918 Parliamentary Qualification of Women Act passed - enabling women to stand as a Members of Parliament
1919 First woman to take a seat in Parliament - Nancy Astor
1928 Vote given to women on same terms as men
1958 Life Peerages Act entitles women to sit in House of Lords Lady Reading and Baroness Barbara Wooton first to take seats
1960 First female Head of Government - Sirimavo Bandaranaike,
Prime Minister of Sri Lanka
1970 Equal Pay Act
1975 Sex Discrimination Act
1976 Shreela Flather elected first Asian woman councillor in Britain
1979 UK's first woman Prime Minister
1981 Baroness Young becomes first woman Leader of the House of Lords
1984 Britain's first black female mayor - Lydia Simmons, Slough
1987 Diane Abbott elected first black woman MP
1990 Baroness Flather is the first female Asian peer
1997 First BME female government Minister - Patricia Scotland
1997 Proportion of women MPs doubles to reach 18%
1998 Baroness Uddin is the first Muslim woman in the House of Lords
1999 UK's first Asian female MEP - Neena Gill
2002 Introduction of Sex Discrimination (Election Candidates) Act
2003 Baroness Amos is the first black woman appointed to Cabinet
2003 Baroness Amos is first black woman Leader of the House of Lords
2006 Work and Families Act
2007 Baroness Scotland is first black woman Attorney General
2007 100 years since first woman councillor appointed
2008 90 years since women over age of 30 secured the vote