Vince Cable is too old to be Liberal Democrat leader, allies of frontrunner Jo Swinson have claimed, as they insisted the party must not go “from the dad to the grandad” when Tim Farron is replaced.

Senior party sources view Ms Swinson, who is yet to announce that she will run, as the overwhelming favourite to take over from Mr Farron, with supporters of the current leader expected to “swing behind” the newly elected MP for East Dunbartonshire.

Mr Farron announced his shock resignation on Wednesday as he said it would be “impossible” to continue in the role while remaining “faithful to Christ" after a bruising election campaign in which he was repeatedly grilled over his views on abortion and gay sex.

Mr Cable, 74, former health minister Norman Lamb and former energy secretary Sir Ed Davey have all been floated as potential successors but it is the 37-year-old Ms Swinson who is seen by some within the party as Mr Farron’s “heir apparent”.