The former cabinet minister and Lib Dem peer Baroness Shirley Williams has died aged 90.

In an announcement on Monday, Lib Dem leader Ed Davey said it was “heartbreaking for me and for our whole Liberal Democrat family”.

Williams was one of the disenchanted ex-Labour cabinet ministers who became the gang of four founders of the breakaway and short-lived Social Democratic Party (SDP).

As a Labour minister, Lady Williams, served in the governments of Harold Wilson and James Callaghan in the 1970s rising to become education secretary.

Throughout her political career, both in the Labour Party and subsequently the SDP and then the Lib Dems, Williams was a passionate pro-European.

Davey said: “Shirley has been an inspiration to millions, a Liberal lion and a true trailblazer. I feel privileged to have known her, listened to her and worked with her. Like so many others, I will miss her terribly.

“Political life will be poorer without her intellect, her wisdom and her generosity. Shirley had a limitless empathy only too rare in politics today; she connected with people, cared about their lives and saw politics as a crucial tool to change lives for the better.

“As a young Liberal, Shirley Williams had a profound impact on me, as she did on countless others across the political spectrum. Her vision and bravery, not least in founding the SDP, continues to inspire Liberal Democrats today.

“Rest in peace, Shirley. My thoughts and prayers are with your family and your friends.”