His actions were at first blamed on exhaustion but, arriving at London's Heathrow's airport, Darren denied this.

I would understand if the Christian Aid people in Jamaica feel disappointed but I must stress that we are not angry with Darren

Christian Aid's Dominic Nutt

He said "it's a long story", insisted he had delivered a speech "to the cameras and the kids" and then drove off without elaborating further.

The father-of-three from south London was visiting Jamaica on a scheduled four-day mission as a goodwill ambassador for Christian Aid.

The climax was to be a keynote speech for World Aids Day on Friday night, at a candle-lit vigil in remembrance of those who have died from the disease.

Darren's decision to cut short his tour earlier on Friday followed a morning of negotiations.

The TV personality opted not to take part in a BBC Radio 5Live interview to discuss World Aids Day.

Luggage packed

BBC News Online was scheduled to conduct a telephone interview with Darren - only to be told he had a stomach upset and was unable to take part.

Staff from Christian Aid, who paid for his trip, said at one point he packed his luggage and left Ligunae Club Hotel, returning only after he was given the day off.

But Dominic Nutt, a Christian Aid spokesman who met Darren off the flight, defended him.

"I understand that he was tired. He's done a lot of work for us in raising this issue.

Darren with a girl from a Kingston children's project before his departure

"He has done two full days out there which has been very valuable but he decided to come home a day early.

"I expect he has seen a lot, including children and adults with Aids, and that can be very distressing."

He said Darren was one of several people due to address Friday night's meeting and they were "disappointed" he did not make it.

"I would understand if the Christian Aid people in Jamaica feel disappointed but I must stress that we are not angry with Darren."

He said the Big Brother star, the third last member of the TV house to be evicted, had worked for them on four previous occasions.

World Aids crisis

They were "very appreciative" of everything he had done for them, Mr Nutt added.

"By the end of the decade there will be 10m Aids orphans and celebrities like Darren are helping to alert the world to this crisis," he added.

On Friday, Darren had spoken of the distress he felt confronting the effect of HIV/ Aids on people in Jamaica, a country with one of the world's highest rates of the disease.

Darren Ramsay: Prior to complaining of exhaustion

In a statement Christian Aid said both the charity and Jamaica had benefited from Darren's work in spreading the message of safe sex.

It said: "Darren's visit will boost awareness both in Jamaica and in the UK about the real impact of Aids. Celebrities like Darren help us to focus attention on these critical issues from which too often people turn away."

The development agency added: "We do understand that seeing people who are ill and possibly dying of Aids can be quite distressing."