UNTIL the other day, I had hardly given the new five pound note a second thought. I vaguely knew there were some people who were angry that it had Winston Churchill on it; I also knew other people didn’t like the fact it was plastic rather than paper. But was there really anything to get upset about?

For a start, who could be more suitable for a place on the national currency than the man who led Britain to victory in the Second World War? And isn’t plastic an improvement on paper anyway? Just think: from now on, when the barman puts your change down in a cold pool of beer, you can just wipe the note clean. You can also stop worrying about leaving money in your pocket before you put your trousers in the wash. It all looks like an improvement to me.

But then a rather disturbing piece of news started to leak out. The new five pound note, complete with a scowling Winston Churchill, was not all it seemed to be. Rumours started to circulate about what the new note was made from and eventually the Bank of England confirmed the truth: included in the ingredients was tallow, a substance made from the fat of a dead cow. In the past, tallow was widely used in candles and soap but its use in money, as a lubricant, was a new development. For the first time, money would include a disturbing new ingredient: the remains of a dead animal.

Naturally, vegetarians and vegans, who eschew all animal products, were horrified by this news, but the reaction to them from meat-eaters was sneering. Some asked why vegetarians and vegans were so worried about money made from animal products – it’s not as if they have to eat the money is it? There were others who joked that they would be prepared to spare vegetarians their moral dilemma by taking the new fivers off their hands for nothing. Basically, it was all being treated like a big joke

However, for those, like me, who judge themselves and others by how they treat animals, the new five pound note is a serious issue. There are all kinds of questions you can ask to judge the moral health of a nation, such as: is its president an arrogant bigot with bad hair? But the most revealing question is this one: how does a nation treat its animals? With respect, or with such disdain that they will casually use its flesh and bones to make money?

Perhaps an example of how vegans and vegetarians think will help. This weekend, with a few friends, I’ll be attending Vegfest, a celebration of veganism being held at the SECC in Glasgow. The event is open to everyone, and part of its mission is to promote a more ethical lifestyle. But the terms and conditions of entry are interesting. “Please do not bring any animal products onto the site in any form,” says the small print. “This is a vegan event.”

For some non-vegetarians, that will look like a rather extreme condition, but it is a reflection of how seriously vegans and vegetarians take the treatment of animals. People may avoid meat and animal products for different reasons – for some, it will be about health (vegetarians are more likely to have lower rates of cancer and heart disease); for others it will be about the principle of killing and eating another animal. But for most, it is simply about weighing an animal’s life against the ultimately trivial, and unnecessary, desire of a human to eat it. Or make shoes or handbags from it. Or, indeed, put it in a five pound note.

The question is: how should vegetarians respond to the furore over the fiver? My first reaction was that, in future, I would ask for all my change to be given in coins, but talking to Tim Barford, the organiser of Vegfest, changed my mind. There are very few areas of modern life, says Mr Barford, that do not abuse animals as products. Use a mobile or laptop? Chances are they will contain stearic acid, which is derived from cows. The same applies to the tyres on buses and bikes. Even the tarmac you walk on is likely to include crushed animal bones.

The point is that vegetarians and vegans have to be pragmatic and focus on the bigger fight. Of course, we should campaign against the five pound note and encourage the Bank of England to use alternatives to tallow (which do exist) but Vegfest this weekend will be accepting the new fiver because the organisers recognise that vegans and vegetarians have to live in a world constructed by others who do not hold the same values. There is also a danger that someone who signs the petition against tallow in money will think they have done their bit and forget about the bigger point, which is to convert as many people as possible away from meat eating and towards a lifestyle that does not abuse animals.

And the signs that is happening are already good. Vegetarianism has been growing for decades but the recent growth in veganism has also been remarkable. Largely led by teenagers and young people – as all the best radical movements usually are – the number of vegans in Britain has risen by more than 360 per cent over the past decade. In 2006, some 150,000 people were vegan; last year it was 542,000. Some of those will have adopted veganism through bloggers and Instagram because they think it’s trendy and will drift back to eating meat in later years, but the direction of the trend is clear: a diet based on non-animal products is growing fast.

The hope is that vegan and vegetarian campaigners, and events like Vegfest, can accelerate the trend, even though the current political landscape does not look friendly. A few weeks ago I was at an event at which Jackie Kay, the new Scots makar, read a poem, Extinction, that listed everything in life that Nigel Farage and his like despise - Greens, Europeans, Guardian readers, etc – and right at the end of the list she added vegetarians, and I can understand why – vegetarianism is still seen by some as eccentric and extreme and evidence of a dubious, leftie world view.

The reality is different. For a start, I’m vegetarian and the opposite of a leftie, but vegetarianism is far from eccentric and is increasingly supported by solid evidence and the forward thrust of science. The World Health Organisation has now put the cancer question beyond doubt – processed meat causes cancer – but increasingly scientific research is also raising the real possibility of artificial meat grown from animal stem cells. Once that is readily available, what possible justification could people have for eating meat?

However, I’d like to leave the last word to that man who sits scowling from the front of the new five pound note: Winston Churchill. Writing in 1931, the great man predicted a future that many would have found unlikely. Man, he said, will eventually realise the absurdity and inefficiency of breeding a whole animal to eat only bits of it and will grow the parts separately instead. It was a radical idea at the time, but it is now about to happen. And who’s to argue with the man on the front of the new five pound note?