Mr Tatchell is on trial at Canterbury Magistrates' Court charged, under the little-used 1860 Ecclesiastical Courts Jurisdiction Act.

The Labour MP Tony Benn and Dr Evan Harris, a Liberal Democrat MP, are expected to be called as a character witnesses for Mr Tatchell.

Mr Tatchell can also count on the support, if needed, of the actress Vanessa Redgrave, and broadcaster Ludovic Kennedy.

Tony Benn MP: Character witness

The trial follows an incident in Canterbury Cathedral on Easter Sunday when Mr Tatchell and six other members of the gay rights group OutRage! stormed the pulpit and accused the Archbishop of Canterbury, Dr George Carey, of discriminating against homosexuals.

If found guilty, Mr Tatchell faces a maximum of two months in jail.

The case has highlighted divisions in the church over homosexuality, and the Bishop of Edinburgh, the Right Reverend Richard Holloway, has written a character reference in support of Mr Tatchell.

Giving evidence on Monday, Mr Tatchell said he considered Dr Carey no different from senior members of the white church in South Africa which had supported apartheid.

"The shame is not our defence of human rights but the Archbishop's defence of discrimination," he told the court.

Giving evidence, Mr Tatchell, a founder member of Outrage!, said the group had planned the protest two weeks in advance.

But he denied that he intended to cause offence or shock to the 1,000-strong congregation.

He told the stipendiary magistrate, Michael Kelly: "Our plan was to go to Canterbury Cathedral on Easter Sunday and stage a brief peaceful protest to highlight Dr Carey's support for discrimination against lesbian and gay people.

"Easter Sunday was chosen simply because it was a high-profile event where the Archbishop and the Church of England were courting publicity.

"We made a very clear decision that we would not interrupt the sacred part of the service."

'Unseemly and inappropriate' conduct

The last time anyone was prosecuted under the 1860 Ecclesiastical Courts Jurisdiction Act was 32 years ago when protesters used a Methodist service attended by government ministers at a Labour Party conference in Brighton to demonstrate against the Vietnam War.

Robert Montague, prosecuting, said the campaigners' conduct on 12 April was "unseemly and inappropriate" in a place of worship but he said Dr Carey stood aside and there was no physical violence.

"The prosecution say that by coming to Canterbury Cathedral that Easter Sunday morning with his associates and acting in the way that he did Tatchell embarked on what may be deemed inappropriate action. It was unseemly. It was indecorous," said Mr Montague.

The court was shown BBC footage taken during Dr Carey's Easter sermon. Mr Tatchell led a group of OutRage! protesters onto the pulpit after one member distracted a verger by pretending to have an asthma attack.

The archbishop's pulpit was taken over by protesters

Then Mr Tatchell went up to the pulpit. "There was no obstruction," he said.

"No-one did anything to stop me. I just walked into the pulpit. Dr Carey may have moved to the side perhaps half a step. I didn't touch him in any way. I spoke in a loud clear voice in order that I could be heard.

"Throughout the whole incident in the pulpit I was focused solely on delivering the statement I had planned."

A superintendent of the Canterbury police, John Grace, who was in the congregation, tried to remove him and struggled to release the microphone away from Mr Tatchell.

One of the stewards tried to help police by hitting Mr Tatchell's hand as he held on to a pillar.

Mr Tatchell told the court that he never intended to cause any damage or offence. He said that he wanted to speak out because for eight years Dr Carey had refused a diaologue with homosexuals.