More than one-third of the British public no longer wants a monarchy, according to a phone-in poll after a live television debate on the future of the institution.

A record 2.6 million viewers called in votes after Carlton Television staged a live programme, Monarchy: The Nation Decides, with 34 per cent of callers saying that they no longer wanted a hereditary head of state. After the show, which at times descended into slanging match, 66 per cent said they wanted the institution to continue.

Regional difference of opinion were evident, with 56 per cent in Scotland voting against the monarchy, Northern Ireland split equally and Welsh viewers marginally in favour, while the audience in England was largely pro-monarchy.

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Carlton executives extended the time limit for calls after thousands complained they could not get through before the deadline in the biggest telephone poll ever staged in the UK.

Steve Clark, Carlton's head of factual programmes, defended the boisterous and, at times, aggressive debate, asking: "Is the standard of debate in the House of Commons at Question Time any better than that?"

The programme consisted of pre-recorded statements from royal experts interspersed with live debate from panellists and reaction from the audience. Some of the panellists were furious about the debate. The former Downing Street press secretary Sir Bernard Ingham said it had been "a disgrace". He wished he had not taken part and likened the level of discussion to that of a pub brawl.

Filmed at the National Exhibition Centre in Birmingham with an audience of some 3,000 people, the debate was heated, but seemed to shed little light on the issue. The confusion increased as thousands of viewers trying to get through on the 14,000 telephone lines allocated to the poll complained that they could not get connected. Some said that they tried to call for hours but were unable to poll their votes, while others were able to vote repeatedly by pressing phone redial buttons.

The tone of the discussion, hosted for Carlton TV by the ITN newscaster Trevor McDonald, was set early on when Stephen Haseler, chairman of the pressure group Republic, said that the real issue was whether British people had a right to choose their head of state.

The Tory MP Steven Norris (Epping Forest) was due to join the debate but left without taking part. He said: "I realised within a few minutes that this was simply not the kind of programme that I wanted to be part of ... I think it was utterly trivial and patronising."

In the discussion the author Frederick Forsyth accused journalists of "muck-raking" with regard to the Royal Family. There was a boisterous reaction when the agony aunt Claire Rayner insisted that people wanted to be citizens and not subjects to a hereditary monarchy.

The Mirror journalist James Whitaker said that he was "let down" by the scandalous activities of members of the Royal Family. The former Sunday Times editor Andrew Neil said they were not value for money. "But perhaps the biggest price we pay for the monarchy is not to be found in any balance sheet; it's the depressing signal that wealth, power and position are still inherited, rather than earned," he said.