The petition launched by the Coalition for Marriage (C4M) has become the biggest campaign this parliament, after passing more than 300,000 signatories shortly after the government launched its “sham consultation” on proposals to redefine marriage.

The C4M petition calls on the government to leave the current definition of marriage alone, which currently defines marriage as the voluntary union between one man and one woman for life.

It was launched in response to government plans to consult on how to introduce same-sex marriage, by Lynne Featherstone, the equalities minister.

More than 100,000 signatures have been added since the government consultation was launched on 15 March.

Dr Dave Landrum, director of advocacy at the Alliance, said: “In recent weeks, the scale of the opposition to government proposals to redefine marriage has become abundantly clear.

“Regardless of the sham consultation, this has been seen in public debates and in the way that the C4M petition continues to break records. With a hung parliament a distinct possibility at the next general election, any party seeking to hold the reigns of power would do well to listen to the will of the people on this profoundly important issue.”

Colin Hart, C4M campaign director, welcomed the huge rise in numbers and said that this was further evidence the government plans to redefine marriage were wrong and should be scrapped.

“There has been a staggering response to the C4M petition, launched last month, which shows just how many ordinary men and women care about this issue.  What has been particularly interesting is the jump in numbers backing the petition since the government unveiled its sham consultation,” said Mr Hart.  

“The equalities minister, who launched the government consultation, has already made it clear that she will not listen to those who oppose the redefinition of marriage.”

And in a new development the European Court of Human Rights issued a ruling that calls into question the whole legal basis of the government’s arguments for making this change.

Mr Hart added: “There is no need to redefine marriage as civil partnerships already give all the legal rights of marriage to same sex couples.

“Redefining marriage would have all sorts of unintended consequences as the institution of marriage is woven into 800 years of our laws, history, education system and culture.

“It would also be profoundly undemocratic as none of the main political parties put this in their manifestos and a recent ComRes poll found 70 per cent of people oppose redefinition of marriage.”