Secularists, Christians and a gay rights campaigner have struck up an unlikely alliance in support of free speech.

Veteran gay rights campaigner Peter Tatchell was joined outside the Houses of Parliament this morning by The Christian Institute's Simon Calvert and Keith Porteous Wood of the National Secular Society.

They were calling for reform of Section 5 of the 1986 Public Order Act, which outlaws "insulting words or behaviour".

The campaigners argue that Section 5 dangerously restricts freedom of speech and want to see the word "insulting" removed.

Tatchell was arrested under Section 5 whilst protesting against Iran's treatment of homosexuals.

The campaigners carried placards saying "do you know your horse is --- " in reference to an Oxford student who was arrested under Section 5 when he said to a policeman, "Excuse me, do you know your horse is gay?" Police accused the student of homophobia but he was later released after prosecutors abandoned the case.

Christians have also been affected by Section 5. Police officers warned Jamie Murray that the display of passages from the New Testament in his Christian cafe could be in breach of Section 5.

Christian hotel owners, Ben and Sharon Vogelenzang, were charged under Section 5 after a row with a Muslim guest over breakfast. Their case was eventually thrown out by a district judge but the high profile court case had a "devastating" impact on their business, which subsequently suffered an 80 per cent drop in income.

The campaign has gained cross-party support and is being led in Parliament by David Davis MP.

The Home Office is due to report on its consultation into Section 5.