The initiative launched by a group called the National Secular Society (NSS) follows atheist campaigns here and elsewhere, including a London bus poster which triggered protests by proclaiming "There's probably no God."
"We now produce a certificate on parchment and we have sold 1,500 units at three pounds (4.35 dollars, 3.20 euros) a pop," said NSS president Terry Sanderson, 58.
John Hunt, a 58-year-old from London and one of the first to try to be "de-baptised," held that he was too young to make any decision when he was christened at five months old.
The male nurse said he approached the Church of England to ask it to remove his name. "They said they had sought legal advice and that I should place an announcement in the London Gazette," said Hunt, referring to one of the official journals of record of the British government.
So that's what he did -- his notice of renouncement was published in the Gazette in May 2008 and other Britons have followed suit.
Michael Evans, 66, branded baptising children as "a form of child abuse" -- and said that when he complained to the church where he was christened he was told to contact the European Court of Human Rights.
The Church of England said its official position was not to amend its records. "Renouncing baptism is a matter between the individual and God," a Church spokesman told AFP.
"We are not a 'membership' church, and do not keep a running total of the number of baptised people in the Church of England, and such totals do not feature in the statistics that we regularly publish," he added.
De-baptism organisers say the initiative is a response to what they see as increasing stridency from churches -- the latest last week when Pope Benedict XVI stirred global controversy on a trip to AIDS-ravaged Africa by saying condom use could further spread of the disease.
"The Catholic Church is so politically active at the moment that I think that is where the hostility is coming from," said Sanderson. "In Catholic countries there is a very strong feeling of wanting to punish the church by leaving it."
In Britain, where government figures say nearly 72 percent of the population list themselves as Christian, Sanderson feels this "hostility" is fueling the de-baptism movement.
Theologian Paul Murray at Durham University disagrees. "That is not my experience," he said, but concedes that change is in the air.
"We are in an interesting climate where Catholicism and other belief systems have moved into the public, pluralist arena, alongside secularists," he said.
De-baptism movements have already sprung up in other countries.
In Spain, the high court ruled in favor of a man from Valencia, Manuel Blat, saying that under data protection laws he could have the record of his baptism erased, according to a report in the International Herald Tribune.
Similarly, the Italian Union of Rationalists and Agnostics (UAAR) won a legal battle over the right to file for de-baptism in 2002, according to media reports. The group's website carries a "de-baptism" form to facilitate matters.
According to UAAR secretary Raffaele Carcano, more than 60,000 of these forms have been downloaded in the past four years and continue to be downloaded at a rate of about 2,000 per month. Another 1,000 were downloaded in one day when the group held its first national de-baptism day last October 25.
Elsewhere, an Argentinian secularist movement is running a "Collective Apostasy" campaign, using the slogan "Not in my name" (No en mi nombre).
Sanderson hopes rulings in other European countries will pave the way for legal action in Britain, since European Union directives require a level of parity among member states' legislation.
"That would be a good precedent for us to say to the British Information Commissioner: Come on, what's your excuse?" said Sanderson.
The bus-side posters that hit London in January sported the message: "There's probably no God. Now stop worrying and enjoy your life."
The scheme was in response to pro-Christian adverts on buses directing passers-by to a website warning those who did not accept Jesus would suffer for eternity in hell.
Comedy writer Ariane Sherine, mastermind of the British bus campaign that saw a copycat version in Barcelona and other cities, said she backs the "de-baptism" movement but insisted the two initiatives were separate.
Sanderson meanwhile remains resolute. "The fact that people are willing to pay for the parchments shows how seriously they are taking them," he said.