A Catholic school in Carshalton which encouraged pupils to sign an anti-gay marriage pledge did not break any laws it has been concluded.

St Philomena’s Catholic High School for Girls was at the centre of a row after sixth form girls were invited to sign a petition against gay marriage called the Coalition for Marriage.

Education Secretary Michael Gove launched an investigation into claims the Catholic Education Service broke impartiality rules on gay marriage by writing to nearly 400 state-funded Roman Catholic secondary schools in March inviting them to back the petition.

In a letter to the National Secular Society dated June 18, Nick Gibb, the Minister of State for Schools said that the Secretary of State examined the evidence in detail taking into account the religious character of St Philomena’s School.

He found on balance the school had worked within the legal framework.

However, the letter goes on to say: "He is concerned, though, that the letter the Catholic Education Service to the school unintentionally blurred the distinction between discussing issues that are a matter of faith and promoting partisan political views.

"This may have led to some schools not presenting a sufficiently balanced pictures to their pupils.

"The Secretary of State has, therefore, written to the Catholic Education Service to express his concern."

The matter was raised after a sixth form pupil spoke out and said girls had been "encouraged" to sign the anti-equality pledge by the school’s headmistress.

Youngsters at the school were shown a presentation on religious opposition to the government’s proposals to allow gay couples to marry in civil ceremonies.

A Department of Education spokesman said they wrote to St Philomena ’s to remind them of the importance of carrying out their statutory duties.