VINCE Cable's public spat with fellow Liberal Democrat grandee Sir Menzies Campbell over his contact with Ed Miliband continued yesterday when the Business Secretary insisted he was neither embarrassed nor apologetic over talking to other politicians in a "sensible, grown-up way".

Sir Ming, the party's former leader, ticked off his colleague for texting the Labour leader; Mr Cable is regarded on the more social democrat wing of the Lib Dems and was once an aide to the late Labour leader John Smith.

"The success of this coalition depends upon everyone who participates in it being a full subscriber, and I don't think, we were using the expression pick and mix a little while ago.

"I don't think it helps a partnership to suggest that you may already be looking for another partner," said Sir Ming.

He asked what would disaffected Tories make of a senior Lib Dem figure cosying up to a senior Labour one.

Mr Cable insisted he had "no ambiguity" about his commitment to the Lib-Con Coalition, saying: "I really don't understand the fuss about very, very occasionally having meetings with Labour politicians and other people across the political spectrum."

Asked, to use Sir Ming's phrase, if he was giving an amber light to trouble-makers, the Secretary of State replied: "I am not encouraging people to make trouble."