Lingerie queen Aliza Reger reveals why you should NEVER put your bra on back to front and 'swivel' it round (and recalls the time Princess Diana popped into the store to buy her delicates)

• e-mail

She is the owner of one of Britain's most beloved lingerie brands, so it is perhaps of little surprise that Aliza Reger is not short of opinions when it comes to what women wear underneath their clothes.

In an exclusive interview with FEMAIL the businesswoman, who runs Reger, the brand founded by her mother Janet, blasted neon knickers and ill-fitting underwear - and explained why so many women are wrong to fasten their bras back to front.

She also shared the secret shopping habits of some of the brand's many celebrity customers, including Lady Diana Spencer, who paid a visit to the Janet Reger Knightsbridge boutique shortly after her engagement to Prince Charles.

This year the company celebrates 50 years of enticing and delighting women with their sensual, feminine designs.

Queen of lingerie: Aliza Reger is the owner of luxury lingerie brand Janet Reger, which was founded by her mother and this year celebrates its 50th anniversary

Asked for the advice she would give other women, Aliza said underwear should be collected, just like shoes.  

'It makes me absolutely nuts,' Eliza said. 'You don't wear one pair of shoes all the time so why would you wear one bra?' 

She continued: 'You need a good sports bra, you need a black lace bra. Would you wear a black lace bra to the gym? Absolutely not, and if you did, you shouldn't. But going out for a lovely dinner with your husband, boyfriend, lover, would you wear a hideous sports bra? Absolutely not. Wear your lovely black lace bra. 

'You wouldn't be tottering around the park in your fabulous 9cm brand new, beautiful suede shoes, you would wear trainers.'  

Celebrity choice: Princess Diana, left, bought her wedding trousseau from Janet Reger. Right, supermodel Helena Christensen models a swimsuit from Reger by Janet Reger at Debenhams

Another 'horrible' habit Aliza wants to stomp out is the way many women put on their bras back to front before 'swivelling' them around their body.  

She said: 'Instead put both arms through the straps, put the straps on your shoulders, bend down and let your boobs fall into the cups. 

'When they are inside the cups, come back up and reach behind to fasten, you may need a bit of practice to do this.  

'If for any reason you are unable to bend down or reach backwards then do this: Do the bra up at the front but have it around your waist and then gently raise it up and pull the straps up, this should cause less twisting and a better shape than doing it up under your chest back to front.'

Janet Reger revolutionised the British woman's underwear drawer when she launched her collection in the 1960s, offering shoppers unashamedly flirty French lace knickers at a time when stores were stocked with utilitarian styles fashioned from flesh-coloured nylon.

'The niche that the Reger brand is in is the luxury, glamorous, spoil yourself,' Aliza said. 'We're not pretending to be sporty or the practical element - you know, everybody needs a new t-shirt bra because that's what you need - but that's not what we do. 

Pioneer: Janet Reger, pictured right and left with daughter Aliza, revolutionised the British woman's underwear drawer when she launched her lacy, feminine designs in the 1960s

'They come looking for a bridal bra, they come looking for a beautiful, glamorous pretty, something that's a little bit different, something that's going to make them feel good. Something they're going to put in their bag and you know take it out when they get home and think "oh, that's so lovely".' 

Sultry: Joan Collins posing in Janet Reger

The brand's colourful bra and knickers sets went on to attract a string of celebrity clients, including Paris Hilton, Bianca Jagger and Jerry Hall. Katie Holmes even bought her entire wedding trousseau from the Janet Reger range.  

Reflecting on the secret to the brand's longevity, Aliza explained it was a mixture of its history and its willingness to adapt. A diffusion line of lingerie and swimwear is available at Debenhams.

Aliza said: 'I think we are now considered a British heritage brand and we have been around for so long that there is an element of trust and I think it is very important to keep reinventing yourself, keep reinventing what you do.' 

Growing up so intimately with the brand - 'It is part of me,' Aliza said - means she has become a veritable expert in the field of women's underwear, and is what has attracted A-list celebrities to the Reger brand. 

Music icons Madonna and Tina Turner and Hollywood heavyweights Elizabeth Taylor, Joan Collins and Nicole Kidman are just a handful of the previous clients Aliza can reel off the top of her head. 

Aliza revealed how when it comes to A-list clients, each needs a different approach.  

Ultimate luxury: The Janet Reger boutique on Bond Street in 1983

The Saudi Arabian princesses, for example, wanted to be advised on the best pieces to purchase. 

Aliza recalled: 'We would go with shade cards every day because they would want new colours - and they spent fortunes.' 

Meanwhile original rock chick Courtney Love required personalised service when she visited London. 

'I remember having to go to the Lanesborough [Hotel, in Knightsbridge] with one of my assistants. She wanted everything brought to her.... She was very larger than life.'

There was no such fuss for Lady Diana Spencer, who came to the legendary Knightsbridge boutique following her engagement to Prince Charles in 1981.  

'Princess Diana came into the shop when she was engaged, she came in and bought her trousseau,' Aliza revealed.

Now as the brand looks to the future, Aliza has turned her attention to bringing the luxury and sumptuousness the Reger name is known for into homeware. A new line of linens, fragrances and collectibles will be launching in collaboration with a major British retailer next year. 

Reflecting on what her beloved late mother would have made of the brand's milestone celebrations, she added: 'I don't think she would have questioned it would still be here 50 years on... 

'She saw the 21st anniversary, the 25th anniversary, she saw 35 years... I don't think she would have been hugely surprised to know we are still around. 

'It is quite emotional and I would like to think that it will continue after me.'