LIBERAL Democrat HQ has insisted Sir Vince Cable will not be relinquishing his party leadership “any time soon” but talk of changing the rules on electing the leader is fuelling speculation that the 75-year-old’s time at the helm is coming to an end.

It is suggested that the MP for Twickenham will use his keynote speech to the Lib Dem conference in Brighton next month to propose plans to allow people to run for the party leadership who are not an MP.

This would, of course, open the way for MSP and former MP Willie Rennie, currently the leader of the Scottish Lib Dems, to seek the bigger role.

When Sir Vince succeeded Tim Farron as party leader following the 2017 General Election, there was speculation that he had done so as a caretaker; that his deputy Jo Swinson, the 38-year-old MP for East Dunbartonshire - who gave birth to her second child in July - would take over at some stage before the next General Election. This is due on May 5 2022, within four days of which Sir Vince will enter his 80th year.

Asked about the prospect of Sir Vince standing down as leader, a party source said: "He's not about to stand down or use the speech to stand down. There are no plans to step down any time soon."

It is expected that the Lib Dem leader will at conference unveil proposals to create a registered supporters scheme, similar to the one that allowed 180,000 people to vote in the Labour leadership elections.

Rules will also be rewritten so that supporters will need to be enrolled for at least 12 months before voting, to prevent any infiltration or undue influence by rival parties.

Sources suggested that Sir Vince hoped to emulate the success of Justin Trudeau's Liberal Party in Canada, which introduced the changes and went from third to first place in its 2015 election victory.

A consultation on the proposed changes is expected to last several months.

The party currently has 12 MPs; four of whom are Scots: Ms Swinson; Orkney and Shetland MP Alistair Carmichael, the former Scottish Secretary in the Lib-Con Coalition; Christine Jardine, who represents Edinburgh West and Jamie Stone, who is MP for Caithness, Sutherland and Easter Ross.

Some UK parties have had leaders who have not been at Westminster. The highest profile is Nicola Sturgeon, the current SNP leader and First Minister. Natalie Bennett, who was not an MP, led the Green Party between 2012 and 2016. She stood unsuccessfully at the 2015 General Election.