Northern Ireland Protestants who are anti-gay are hypocrites because King William of Orange had male lovers, a leading gay rights activist has claimed.

Speaking in Belfast, Peter Tatchell claimed that Democratic Unionist politicians such as Iris Robinson are victimising gay people in the province.

His claims about King William are particularly insulting to Protestants, who revere him as the saviour of Protestantism in Ireland.

His defeat of King James II at the Battle of the Boyne in 1690 is commemorated by Northern Ireland Protestants with parades on the 12th July.

The Orange Order, an exclusively Protestant organisation that organises The Twelfth celebrations, takes its name from William’s Dutch principality.

Married to James’ Protestant daughter Mary, in 1688 William was “invited to invade” England and take the throne. The Roman Catholic James fled to Ireland but was finally defeated and was exiled in France for the rest of his life.

William and Mary’s joint reign secured the Protestant succession.

Historians disagree about William’s sexual orientation.

Throughout the 1690s many satirical publications mocked William’s lack of mistresses and his closeness to Dutch male courtiers whom he granted English titles.

A spokesman for the DUP said Mr Tatchell was being provocative.

“It is particularly hypocritical for unionist politicians to play the homophobic card when their hero, William of Orange, had male lovers,” the human rights campaigner said ahead of his appearance at tonight’s Amnesty International Pride Lecture in Belfast.

“Iris Robinson’s remarks are part of a pattern of homophobia that seems to characterise sections of Northern Irish society.

“She would never get away with making similar remarks about black or Jewish people.”

Mrs Robinson, the MP for Strangford, was at the centre of renewed controversy last week when it emerged that she likened child abuse to homosexuality at a Commons committee.

She sparked outrage earlier this year when she offered to put gay men in touch with a psychiatrist who claims he can make them straight.

More than 12,500 people have already signed a petition on the Downing St website asking the Prime Minister to reprimand Mrs Robinson.

The Northern Ireland Parades Commission has given permission for Belfast Pride to go ahead on August 2nd without any restrictions.

In August 2007 Belfast city councillor Christopher Staltford led calls for restrictions on future gay parades, claiming he was offended a the placard which read: “Jesus is a fag.”

Belfast Pride is habitually picketed by groups of fundamentalist Christians, but usually passes off peacefully.

Free Presbyterian protesters infiltrated the march in 2006, handing out extracts from the Bible in protest.

Belfast Pride has been held every year since 1991 despite calls from the Free Presbyterians and others to ban it.