Cameron 'f****d things up' on gay marriage, Norman Tebbit blasts as he suggests he should now be able to marry his own son

Lord Tebbit suggested gay marriage should be extended to family members to avoid inheritance tax

Norman Tebbit has launched a foul-mouthed attack on David Cameron, claiming the Tory leader has ‘f***** things up’ buy pressing ahead with gay marriage laws.

The former party chairman’s extraordinary public criticism of the current leadership emerged after the Prime Minister was forced to rely on Labour support to rescue same-sex weddings.

Lord Tebbit said the plans would create inconsistencies, and could be extended to help families avoid inheritance tax, declaring: ‘Maybe I’d be allowed to marry my son.’

Mr Cameron’s leadership has been under sustained criticism for weeks, unable to suppress Tory mutiny over Europe and gay marriage.

Last night he wrote to party activists to build bridges with them after a senior Tory figure reportedly called them ‘mad, swivel-eyed loons’.

In an interview with the Big Issue Lord Tebbit said ministers had alienated traditional Tory voters.

The party leadership had ‘f***ed things up’ and the UK Independence Party would pick up support as a result.

A new opinion poll last night put UKIP just two points behind the Conservatives.

Lord Tebbit added: ‘If [UKIP] make significant gains in the European elections, I know there’s people rich enough to get involved and fund a significant campaign at a general election.’

Discussing the impact of legalising gay marriage, Lord Tebbit suggested it be extended to family members.

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He said: ‘It’s like one of my colleagues said: we’ve got to make these same-sex marriages available to all. It would lift my worries about inheritance tax because maybe I’d be allowed to marry my son. Why not?

‘Why shouldn’t a mother marry her daughter? Why shouldn’t two elderly sisters living together marry each other? I quite fancy my brother!’

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David Cameron, pictured leaving Tory party headquarters in Millbank yesterday, is under pressure to repair relations with the grassroots

Lord Tebbit also questioned whether the gay marriage laws could cause chaos when combined with changes to the rules of succession, which would allow an older female heir to the throne to become monarch.

‘I said to a minister I know: “Have you thought this through? Because you’re doing the law of succession, too.”

‘When we have a queen who is a lesbian and she marries another lady and then decides she would like to have a child and someone donates sperm and she gives birth to a child, is that child heir to the throne?’

Lord Tebbit later admitted he had sworn during the interview. ‘It’s not the language I normally use, but during a long interview I may well have said it,’ he told The Times.

Mr Cameron issued a love letter to Tory activists last night as UKIP closed to within two points in the opinion polls.

The peace offering followed revelations that a senior ally of the Prime Minister had branded the party faithful ‘swivel-eyed loons’. MPs warn that his leadership is in peril amid discontent on Europe and gay marriage.

The scale of the crisis was shown last night by a new poll that puts the Tories down five points on just 24 per cent, 11 behind Labour.

UKIP – up six points in a month – was on 22 per cent, double the level of Lib Dem support.

In his email to party members, Mr Cameron said: ‘We have been together through good times and bad. This is more than a working relationship; it is a deep and lasting friendship.’

Referring to reports that Tory co-chairman Lord Feldman – a tennis partner of Mr Cameron – had insulted them, he added: ‘ I am proud to lead this party. I am proud of what you do. And I would never have around me those who sneered or thought otherwise.

‘We are a team, from the parish council to the local association to Parliament, and I never forget it.’

The dire poll ratings will fuel the discontent of Tory MPs who warned yesterday the number prepared to force a leadership election has risen in recent days.

If 46 write letters to Graham Brady, chairman of the backbench 1922 Committee, there would be a vote of no confidence in Mr Cameron.