The first female Speaker of the House of Commons Betty Boothroyd has died aged 93.
She served as Speaker from 1992 to 2000, before going on to become a baroness in the House of Lords from 2001.
The current Speaker Sir Lindsay Hoyle described her as "an inspirational woman" who was known for her "no-nonsense style".
She was the Labour MP for West Bromwich West from 1973 to 2000.
"To be the first woman Speaker was truly groundbreaking and Betty certainly broke that glass ceiling with panache," Sir Lindsay said.
"Betty was one of a kind. A sharp, witty and formidable woman - and I will miss her."
The flags in Parliament are being flown at half mast and the House of Commons held a one minute silence before business began on Monday.
MPs will get the chance to pay formal tributes on Tuesday.
Prime Minister Rishi Sunak said Baroness Boothroyd was a "remarkable woman" praising her "passion, wit and sense of fairness".
Former prime ministers have also been paying tribute.
Sir Tony Blair said she was "big-hearted and kind" and Sir John Major described her as "easy to like and easier still to admire".
Theresa May said she had earned "the respect and admiration" of all MPs during her time as Speaker.
Labour leader Sir Keir Starmer described her as a "dedicated and devoted public servant who will be dearly missed".
Betty Boothroyd was born on 8 October 1929 in Dewsbury, West Yorkshire, the only daughter of mill workers.
Growing up in a political environment - her father was a trade unionist - she described herself as coming "out of the womb into the Labour movement".
However, she didn't immediately go into politics, becoming a dancer with the Tiller Girl troupe.
She then took a number of office jobs before getting involved in politics, working for the Labour MP Barbara Castle and on the campaign to elect John F. Kennedy as US President.
In May 1973, after several attempts, she entered Parliament, securing the seat of West Bromwich, later renamed West Bromwich West.
After nearly two decades in Parliament she was elected by her fellow MPs to the position of Speaker of the House of Commons - a job which involves presiding over proceedings in the chamber.
She stepped down from the position in 2000, but continued to be active in politics - calling for a statue in central London to commemorate the part women played in World War Two.
She was also passionately involved in the campaign to keep the UK in the EU.
Alastair Campbell, who was also involved in the campaign, said she was a "total one off".
"One of the kindest, wisest, most loving and loveable women you could ever wish to know."
Clare Short - a Labour minister from 1997 to 2003 - told BBC 5 Live that Baroness Boothroyd "suited being Speaker perfectly, her personality shone through, she had a natural authority.
"She was the one who dropped the wig [traditionally worn by Commons Speakers] because she had her own lovely thick grey curling hair."
Former Scottish Conservative leader Ruth Davidson simply tweeted: "Betty Boothroyd was magnificent."