The lemonade, tea and homemade cakes at the garden party will most definitely be real.

And so too will the guests, many of whom will be wearing frocks dating back to the 1950s.

For just a few hours, the virtual world of Bristol-based vintage retailer Mouse to Minx – which has attracted a following in countries including Denmark, Poland, France and the US – will become a reality in the back garden of Number 7 Christmas Steps, in the city centre.

But once the china cups and saucers have been cleared away, Paula Daly will return to the eccentric online world she has created, in which post-war chintz dresses and knitted tea cosies combine with fictional characters who exist only on the internet.

"Some people out there seem to think there are three people running the business, but it's just one exhausted one," she says, as she sits in the garden at the rear of 17th century terraced townhouse otherwise known as Mouse to Minx HQ.

Paula is referring to Daphne, Dulcie and Doris, the three characters who feature prominently on the Mouse to Minx website, and also on the networking sites Facebook and Twitter.

"It started when I had one mannequin, and I decided to call her Daphne. I thought it was quite a quaint name," says Paula.

"She's been on Facebook as Daphne Thistlethwaite-Smthye for quite some time now. I'm sure most people know she isn't real. At least, I hope they do.

"Then I got two more, which I called Dulcie and Doris. I thought it sounded like a triumvirate of jolly schoolgirl types, and decided to give them characters.

"Daphne is the PR girl and a ruthless brand manager. Doris is quite handy. She does knitting and baking, and is the 'geek minx' in charge of Twitter. Dulcie is the corporate sophisticate."

Are the three characters based upon facets of Paula's own personality?

Paula, 46, just smiles enigmatically in response. However, she agrees that she is an unusual combination of technological whizz kid and nostalgia buff.

"My parents lived in London during the war, and there's a very strong interest in musical theatre in my family, so I know the music and styling of the Forties and Fifties.

"I'm quite happy I was born when I was. As a 1950s housewife I wouldn't have my independence and my own income. But I enjoy the escapism of that unashamed nostalgia – the spotty tea pots and tea cosies, the corsets, and the small diamante brooches of poodles and handbags.

"I've tried to recreate that world of lace tablecloths and afternoon tea on the Mouse to Minx website.

"It's all very tongue in cheek and genteel, with gloves, vintage corsets, and books on etiquette."

Until Paula set up Mouse to Minx – which has been described as "burlesque meets Miss Marple" – she had spent her career in public relations and creative marketing, after graduating with a degree in Fine Art from the University of the West of England in 1992.

She had been creating websites for about 11 years when she decided to create own her own business around her interest in collecting vintage clothing.

Initially, Paula set up a concession in the Bristol shop Ripe in 2005, but then decided to set up her own shop on Christmas Steps, selling vintage clothes and vintage-inspired fashions and products from small designers and design houses.

Last year, she decided to close her shop and concentrate on making Mouse to Minx an online retailer.

"People were very enthusiastic about the shop," she said.

"I'd have been a millionaire by now if compliments had a financial value.

"But although Christmas Steps is a lovely location it's very quiet, so I'm concentrating on the internet as most Mouse to Minx customers are online.

"I've shipped products all around the world. There's quite a following in Denmark and Finland, and also to the West coast of the United States – particularly around San Francisco – and in New York."

Mouse to Mix has its own Minx Club, and there are members in the US, Poland, France, Germany, Canada, Spain, Australia, Italy and Sweden – as well as in Britain. The majority of Mouse to Minx fans in this country live in London, followed by Bristol and then Birmingham.

Such has been the growth of Mouse to Minx that when the annual garden party takes place on Saturday, June 20, admission will be by ticket only for the first time.

It will be an opportunity for anyone who bought a vintage dress at Mouse to Minx in the past five years to come for a Frock Reunion photo opportunity.

And it will also be a chance to socialise for Mouse to Minx members – and Paula's black and white cat Murphy.

"He loves having people around, so he hasn't been very pleased about the shop being closed," says Paula, as Murphy claws at the door trying to get out to see passers-by on Christmas Steps.

Paula's mother died of breast cancer 2003, and all money from the £5 tickets for the Mouse to Minx garden party will be donated to Breast Cancer Research.

"My mother died on my 40th birthday," says Paula. "There were other upheavals in my professional and personal life at that time.

"It made me take stock of what I was doing with my life, and think about what I really wanted to be doing – and the result was Mouse to Minx."

- The Mouse to Minx Garden Party takes place at 7 Christmas Steps, Bristol, BS1 5BS, on Saturday, June 20. Invitation is by tickets only, which cost £5 each. The full ticket price goes to Breast Cancer Research.