Business Secretary Mr Cable endorsed the apology and insisted he also took responsibility for the "collective" decision, but told the BBC's Newsnight programme: "I was sceptical about the pledge but we agreed collectively to do it and I take my share of the responsibility."
Mr Cable said Danny Alexander, now Chief Secretary to the Treasury, was also among those who privately warned the policy was unaffordable.
In a bizarre turn of events, Mr Clegg has also given permission for a video making fun of his apology to be released as a single on iTunes.
A version of the film created by satirical website www.thepoke.co.uk has the Deputy Prime Minister singing his remarks to a pop backing, and received thousands of views in a matter of hours. All profits will go to Sheffield Children's NHS Foundation Trust. Mr Clegg's wife Miriam is a patron of the hospital.
A source close to Mr Clegg said the video was another way of "getting the message out".
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Pope hailed over decision to quit 14:05, Feb 11 2013
The three most senior figures in the Catholic Church in England and Wales have paid tribute to Pope Benedict XVI after the Pontiff announced he was leaving office on grounds of age and infirmity. more
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Britain must make sure its borders are "as open as possible" to genuine foreign business visitors and investment, Business Secretary Vince Cable has said. more
Tributes for killed photojournalist 13:05, Feb 11 2013
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BBC staff threaten one-day strike 13:05, Feb 11 2013
BBC journalists are to stage a one-day strike unless the corporation agrees to end compulsory redundancies, it has been warned. more
Briton death sentence appeal filed 10:05, Feb 11 2013
An Indonesian lawyer representing a convicted British grandmother has formally appealed against the death sentence she received for smuggling cocaine worth 2.5 million US dollars (£1.58 million) into the resort island of Bali in a suitcase. more
Legal action plan in horse meat row 09:05, Feb 11 2013
Legal action over the horse meat scandal is to be mounted in Europe, Environment Secretary Owen Paterson has said as he described the contamination of beef products as a case of fraud against the public. more
Snow triggers weather warnings 06:05, Feb 11 2013
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