Image copyright Cecilia Leslie / Instagram

Think washable nappies, and most of us will envisage a burdensome, time-consuming - not to mention smelly - commitment reserved only for the most dedicated eco-warrior.

But, for many a convert, cloth nappies are a hobby, a passion, and even an obsession.

"Cloth bumming", as it's called in inside circles, is no longer just about the environment or saving money, but also about fashion and the clamour to get the most sought-after designs on your baby's bottom.

Some fans collect nappies in the way others amass handbags. Limited editions are snapped up at lightning speed to be posted for resale at nearly 10 times the retail price.

Social media communities are flourishing and even have their own lexicon.

So what is it about cloth nappies that draws such a cult following?

'Not just a frivolous hobby'

Image copyright Cecilia Leslie / Instagram

Mother-of-four Cecilia Leslie has built up a stash of about 500 nappies.

The full-time midwife is now a cloth nappy "influencer" with more than 22,000 Instagram followers.

Like the vast majority of "real" nappy users, the 32-year-old from Edinburgh originally set out on her "cloth journey" to reduce plastic waste and save money but, over the years, it became a hobby.

Image copyright Cecilia Leslie / Instagram

"I fully intended for my use of cloth to be solely functional. But, once I started, it became more of a case of wanting all the pretty patterns. I joined quite a few communities online, where there was a lot of hype about having all the prints.

"I've got a lot of limited editions, which sell out quickly. It became a bit of a game trying to track them down - I used to source them from Canada, Australia and the USA.

"I paid £60 for a limited edition print that TotsBots brought out when Prince George was born. And I once paid £160 for a pair of limited edition Bumgenius nappies - there were only 100 made."

Image copyright Cecilia Leslie / Instagram

"Some brands will launch a collection a couple of times a year, with about five or six prints each time, and I would buy all five in one go. I've also been known to buy five of the same print if it's one I particularly love."

Is she addicted to cloth nappies? "I think I am. I feel a sense of pride about how nice it looks and it's a conversation starter, especially at baby groups."

Ms Leslie says she's chatted to her husband about how he feels about her nappy habit. "He agreed the money could be better spent, but he said there are a lot worse things I could be addicted to!"

Image copyright Cecilia Leslie / Instagram

And doesn't owning so many nappies defeat the object of a reusable product?

"I do get some negative comments about the size of my collection. Yes, it's more than I need, but those nappies were bought at independent shops, so it's keeping people in jobs, and I use every single nappy I own: none of them just sits on the shelf.

"It's not producing landfill - once Isaac grows out of them I'll sell them on and give other mums a chance to have a really good nappy in excellent condition. So overall it's a positive thing - it's not just a frivolous hobby."

'It became an obsession'

Image copyright Nicola Vandenbrouck

Nicola Vandenbrouck, mum to 17-month-old Drew, admits she's become passionate about colourful cloth nappies.

"I only started cloth-bumming for the pretty colours. I discovered a print called Kaleidoscope and I just thought, 'wow, that is amazing!'

"I bought it and a couple of others, just because they looked cool.

"Off the back of that I started to get into some of the Facebook groups, and it all took off from there and became an obsession," says the quality engineer from Great Torrington in Devon.

"I have about 40 and every couple of weeks, when the doorbell rings with a delivery, my husband complains: 'Not another nappy order!'"

'It helped with my postnatal depression'

Image copyright Zoe Davies Image caption Zoe Davies: "The online cloth nappy community is so supportive"

Zoe Davies, who runs a "nappy library" in St Austell, Cornwall, says using "real nappies" helped her cope with postnatal depression following the birth of her son, Theo.

"It's something to look forward to, with new prints coming out, and they're all happy colours. When you see them hanging out on the line it's pleasure to see - it's a really wholesome thing.

"The online cloth nappy community is so supportive, and the routine and ritual really helped, too. It helped me think that, even though I'm suffering with depression, here's something that I can achieve, something I can do for good."

'Our royal baby nappies crashed the website'

Image copyright TotsBots Image caption A limited edition royal baby print sold out in 90 minutes

Fiona Smyth, director of cloth nappy manufacturer TotsBots, says she was stunned by the reaction to a limited edition print, named Royal Flush, released to celebrate the birth of Prince George.

"We made 500 royal baby nappies and they sold out within an hour and a half. The website crashed. The retailers' sites crashed," she says.

"We charged the normal price (£18) for them but they started appearing on eBay for £150 within a week. We only made 30 of the TeenyFits, which fit babies up to 12lbs, and they're still selling on eBay for £60 - this is for a five-year-old nappy which cost £12 new."

Mrs Smyth adds: "Parents can be quite fanatical [when a new range is about to be released] and start stalking your website. They want to be the first person to buy and get them 'OTB', or 'on the bum', and get their pictures on social media.

"It adds a little bit of joy to something that's not usually that much fun."

'Mums compete over the best collection'

Image copyright Bambino Mio

Carly Baillie is head of product at Northampton-based Bambino Mio, and manages the brand's design output.

"People really care about what their children are wearing. They like to make a statement," she says.

"We currently launch one collection of designs each year, but the appetite for fun designs is getting stronger and stronger."

Image copyright Bambino Mio

Mrs Baillie says Bambino Mio has many loyal fans it describes as "collectors of the brand".

"It does become a cult. A lot of parents buy the whole collection in one go. People write to tell us about their collections and 'stashes', or to request a discontinued print.

"Customers compete, in a sense, over who has the biggest and best collection and who can get their hands on all the different designs. We've produced a chart, so people can tick off the nappies they've collected.

"[Collecting them all] is a big investment, but people enjoy it."