Standing in the palm court of a large central London hotel, to the accompaniment of a lightly plinking piano, Biff Byford, lead singer of 1980s heavy metal behemoths Saxon, is preaching to convert the non- ferrous among us to his cause. "Heavy metal is a tribal music and everyone is a member of the tribe," he explains. "The audience is very, very loyal… especially the Germans. It's not like pop music, where if the next song isn't good enough then forget about it; with our music, people will allow you to be shit sometimes, and that's one of the great things."
A wistful look passes across the features of a man memorably described by one critic as "the dray horse of heavy metal". "The music's not about love," he adds, warming to his theme. "Our songs are more about Richard the Lionheart, steel trains and thunder. But when you do click with a big audience, it can be quite an experience, a massive connection… I suppose you could say it is a religious experience in a way."
For a former miner from Skelmanthorpe, Yorkshire, who started his musical career touring in a tripe van, it's a surprisingly wide-eyed admission. But an apt one, too, considering his latest job.
For Biff Byford now glories in the title of Official World Metal Peace Ambassador; he's the face of a campaign to persuade fans to claim heavy metal as their religion in the 2011 Census. So far, 28,000 have signed up to the Facebook site, and the organisers ' hope that many more will follow – creating the kind of hoo-ha that followed when 390,000 Star Wars fans declared their religion to be Jedi in 2001.
It would be easy to dismiss Byford's campaign, organised by the rock magazine Metal Hammer, as a clever but meaningless bit of PR, and Byford himself admits it's "just a bit of fun" – even offering up his own 10 Commandments of Metal ("Thou shalt not covet thy guitarist's girlfriend" etc). But when you hold up a magnifying glass to this passing piece of cultural fluff, it turns out to be alive with all kinds of hidden significance.
For a start, it may well have proved to be the final nail in the coffin of the traditional census, which has been carried out in Britain every 10 years since 1801. At the time of going to press, an announcement is expected shortly from the coalition Government that 2011's will be the last of its kind. Instead, data from a variety of other sources is likely to go into compiling a cheaper, more regularly updated snapshot of the nation – and one less prone to be skewed by the antics of lank-haired, lightsaber/air-guitar wielding young men called Malcolm.
The Tories never liked what they described as a "snooper's census" anyway, especially with its £500m delivery cost. But while few of us will miss questions such as "What type of central heating do you have?" or the more potentially compromising Who is staying overnight?" on a form filled out, Victorian-style, by the head of household, it's the loss of that deceptively straightforward-sounding question number 20, "What is your religion?" , that should be particularly mourned.
Without it, for example, how would we ever know that, among the nation's 150-plus religious groups, there are 2,368 Christadelphians, 426 Eckists and 123 Voduns worshipping away somewhere out there? More importantly, as campaigns such as Byford's demonstrate, the question is uniquely open to interpretation. And for this reason, it offers future historians a wide window on faith and identity in 21st-century Britain.
The sublime and the ridiculous are never far apart here. Byford's co-conspirator, the Metal Hammer editor Alexander Milas, believes that their campaign "makes a serious point in critiquing the whole notion of the census. We were asking, what defines faith? Because if you take the criteria that are generally used, there's absolutely nothing that excludes heavy metal – many of the practices are the same. If anything, you probably have a more faithful flock than most actual religions do."
Using the same logic, other fledgling campaigns vying for your mark in the "any other religion" box for 2011 include "surfing" and the "Church of the Flying Spaghetti Monster" (aka Pastafarianism), an elaborate spoof belief system with nearly 150,000 worldwide followers, first launched in the US as a protest against the teaching of creationism in public schools.
Jedi is still an option, too, though not necessarily the best for those who'd like to blow a raspberry in the face of organised religion. While its followers in the 2001 Census were classified as having "no religion" by the Office of National Statistics (ONS), some especially zealous elements have now formed an official Jedi church, and are busily taking on all the baggage of an old-school faith.
In 2007, two cousins called Jones who set up the church's Anglesey branch, became the first of their kind to suffer from bona fide religious persecution. One afternoon in late March, while the pair were getting down to some ritual lightsaber practice, a drunken man dressed in a black bin-liner jumped over their garden wall shouting "Darth Vader!" and proceeded to assault them with a metal crutch. In the ensuing prosecution, the court heard that the Joneses had been particularly upset because they believed "very strongly in the church and their religion".
Soon after, there was an incident at Tesco Extra, Bangor, when a church member claimed to have been left "emotionally humiliated" after he was asked to remove his Obi-Wan Kenobi-style brown hood at the check-out. All of which goes to back up Millas's point that faith is where you find it.
Censuses have had a sticky association with religion ever since King Herod's people were handing out the forms in the vicinity of a certain Bethlehem manger 2,000 years ago. And it was the alarmist ideas of a man of the cloth who first inspired the British to adopt this ancient counting exercise, the origins of which can be traced to Egypt in the third millennium BC. In 1798, the Reverend Thomas Malthus published his "Essay on the Principle of Population", which warned that "the power of population is indefinitely greater than the power in the earth to produce subsistence for man". By raising the spectre of future famine, it panicked the government of the day into discovering just how many hungry mouths there were out there to feed.
The question on religion itself, though, was introduced to the British form only in 2001, which goes some way to explain why it's still such a circus ring – not just for those wackily redefining faith in the 21st century, but also for activists with a more serious, political agenda.
A call to Naomi Phillips, head of public affairs for the British Humanist Association, prompts her to swerve her car instantly to the side of the road in order to deliver an impassioned argument as to why this question should be scrapped altogether and why, failing that, we all have a duty not to indulge in any smarty-pants responses of a heavy metal/Jedi/Pastafarian kind and instead place a firm tick in the "no religion" box.
"The census encourages people to claim a religious affiliation without recording whether they are actually practising or not," she says. "A very large minority who tick Christian, for example, are not Christian in practice, and the problem is that the data is used for all sorts of things to do with public policy, to justify the presence of bishops in the House of Lords, state-funding of faith schools, religious broadcasting… With the new Equality Act 2010, local authorities will be using it to make funding decisions too."
It is not just Christianity which gets overly bigged up, according to Phillips. The same is true of Judaism and Sikhism, because if secular members of either of these groups want to record their identity, the only place they can do so is in the religious section of the form. Earlier this year the Sikh Federation threatened to sue the ONS for failing to give them their own tick box in the ethnicity section instead.
"At the moment the census undercounts the non-religious population," says Phillips, "which for non-religious people is very damaging. We are going to do a big public campaign on this – we'll be saying: 'If you're not religious, for God's sake say so.' Don't say you're Jedi or heavy metal; it's extremely important we get a realistic response – especially because this may well be the last census, which means the data could be used for even longer than the 10 years it's used for now."
As Phillips points out, without God, you don't get many state perks: no special holidays, dress-code exemptions or dedicated meals-on-wheels service, but the humanists have at least managed to extract one tiny change to next year's census that could help their cause. A "No religion" tickbox in 2011 replaces 2001's more bleakly nihilistic "None". Phillips hopes this will help swell the atheist head count, which nine years ago stood at 7,274,290 – running in second behind "Christian" as the most common response.
It's worth mentioning, though, that this subtle alteration, just like every other syllable of the census, required deranged amounts of research, consultation and pin-head dancing by the ONS, whose apparent terror of GETTING THINGS WRONG meant they were unwilling to put up anyone for interview for this feature – answering all queries via a series of super-cautious emails.
One religious group equally determined to get their wording right in 2011 are the Pagans. And if they do achieve their aim of being counted as one united horde, then everyone from the heavy metallists to the humanists may find their campaigns knocked into a pointy witch's hat.
While 30,569 people declared themselves to be Pagan in 2001, the Census also logged 7,227 Wiccans, 1,657 Druids and thousands more describing their religion variously as heathen, new age, occult and so on.
The Pagan Dash campaign aims to ensure that next time, all these disparate groups prefix their particular faith strand with the umbrella term "Pagan", so you might, for instance, be "Pagan – polytheistic", "Pagan – goddess follower" or "Pagan – hedge witch".
As Emma Restall Orr, a raven-haired druid priestess better known to her friends as "Bobcat", points out, "There was a campaign like this in Australia and pagan numbers went up sevenfold nationally. Many more people are willing to call themselves Pagan now anyway. In 2001 there were still places where to show a Thor's hammer or a pentacle as a piece of jewellery got you into trouble. There was discrimination in the military, the police force and in the NHS. Those sorts of persecution and ridicule have diminished significantly."
Still, the aim of being properly counted, she says, is "to be able to get funding to help our more vulnerable members – to look after people who have problems at work, children in schools who are being teased, people who might find themselves on the wrong side of the law."
Convicted offenders, incidentally, may already call on the services of the Pagan Federation's scarily named Prison Ministry Manager, Psychobunny.
While Paganism is a good bet to win the golden sickle for fastest-growing religion in the 2011 Census, England and Wales are still home to 37 million self-professed Christians. So what does our national church make of all these heathens, humanists and jokers hell-bent on stealing away its traditional flock?
"I think it shows us that there's a lot of confused thinking about faith identity," says Lynda Barley, the Church of England's head of research and statistics. "People want some roots, they want to be a part of something, but people are out of love with the religious institutions, and they don't want to be aligned with them. In this census question there's very little room for them to say that, and I think some of these groups, no matter how much fun they're having with the question, are actually saying they want some identity in this faith area and they don't know how to articulate it.
"In an ideal world, you'd have three census questions on religion," she adds. "The first on affiliation, the second something on participation – how do you practise your religion? – and the third on belief: do you believe in God, in a personal God? And really those are three totally different axes of faith which people can be any place on, without one necessarily having any correlation with any other – you might be strong in practice but actually be quite agnostic and affiliate to something quite loose. Or you could affiliate strongly, have a strong belief but actually not practice."
The danger, though, is that after 2011 we'll be left with no questions at all. And, according to Catherine Pickstock, reader in philosophy and theology at Emmanuel College, Cambridge, that could be bad for Britain: "Although the census can be seen as a sinister tool of power, its removal could have a disempowering effect upon the collective," she says. "Its removal prevents the organism from knowing itself, understanding the extent of its own variety and historical identity."
An ageing monster of rock leading a spoof religion is very much a part of that variety. Could it even be true, as Barley suggests, that Ambassador Byford is unwittingly gathering an army of lost souls, with a subconscious yearning for some sort of connection with the divine? "Actually, it's the devil that features quite a lot in heavy metal," says Biff, matter-of-factly. "I'm not a big fan of all that devil-worship stuff, but there are a lot of bands, especially Scandinavian, that are into it. I wouldn't burn a church down or fire missiles at people as others have done – but then, some people get a bit carried away with their beliefs, don't they?"
They do, Biff, they certainly do.