Half a million signatures supporting the traditional definition of marriage are being handed in to Downing Street today.

The petition by the Coalition for Marriage supports the legal definition of marriage as the "voluntary union for life of one man and one woman to the exclusion of all others" and expresses opposition to any attempt to redefine it. It was signed by over 550,000 people.

While the list of signatories will be submitted to Downing Street, the full petition of names and addresses will be handed in to the Home Office as it is too large to deliver to No 10, filling more than 30 A4 boxes.

The petition was launched on 20 February in response to the Government's plans to redefine marriage.

Although the petition is being submitted today, it remains open and C4M hopes to reach a million signatures in the coming months.

The delivery to Downing Street is being accompanied by C4M Campaign Director Colin Hart, Fiona Bruce MP and David Burrowes MP.

It comes just before a public consultation on redefining marriage closes on Thursday.

A C4M spokesman said: “We have the biggest active petition in the UK. The petition will remain open because hundreds are still signing every day. Our goal is to reach more than one million names. Today’s hand-over of the first half-million is just the beginning.”