The UK Supreme Court will today hear the case of the Christian guest house owners who were prosecuted for discriminating against same-sex couples.

Judges have twice ruled Peter and Hazelmary Bull, from Cornwall, broke equality laws in the running of their business.

Martin Hall and Steven Preddy had been turned away from the Chymorvah Hotel near Penzance in 2008 under the Bulls’ policy of not allowing unmarried couples to share rooms.

In January 2011, a judge at Bristol County Court ruled the Bulls’ behaviour amounted to direct discrimination on the grounds of sexual orientation, and awarded a total of £3,600 damages to Mr Hall and Mr Preddy.

In February of this year, Mr and Mrs Bull took their case to the Court of Appeal and lost their appeal against a ruling that they had acted unlawfully.

The pair have since taken their case to the UK Supreme Court, the highest court in the land.

The Equality Act 2010 states that it’s illegal to refuse to provide goods and services based upon a person’s sexual orientation and gender identity.

The Bulls have told judges that they think any sex outside marriage is “a sin” – and deny discriminating against Mr Hall and Mr Preddy.

Five Supreme Court justices are scheduled to hear legal argument over two days in London – and are expected to reserve a decision until later.