What will Bronagh Key be wearing at royal wedding?

John and Bronagh Key have had outfits made to suit the dress code of a Westminster Abbey occasion. Photo / Michael Craig

No cleavage, a small hat, and not too much flesh - that's what designer Trelise Cooper had in mind when she created Bronagh Key's dress for the royal wedding.

The Auckland designer has produced a one-off pink and blue outfit for the Prime Minister's wife, with careful attention to the dress code of a Westminster Abbey occasion.

"I would describe it as ladylike, classic and elegant," Cooper told the Herald.

"It's quite understated, and I think the occasion calls for that - the tension between something that's formal but still modern."

Mrs Key said she chose Trelise Cooper because she was a designer whose pieces measured up to the world stage.

The outfit took three weeks and four fittings to complete.

Despite the painstaking attention in its creation, Cooper admitted she was waiting nervously to see how it appeared on television.

"It's something that everybody's interested in, and I think there is a particular look and feel that it has to have.

"I feel we have achieved that, but at the same time it's a bit nerve-racking. I'm glad I'm not doing the wedding dress."

The knee-length dress is marine-blue with a bodice of lilac pink, and includes a marine-blue silk coat, a pink clutch, gloves and a Dolly Varden hat.

The fitting design and use of cotton lace brought it into line with current trends, said Cooper.

The Keys' wedding invitation gave clear instructions for the men's dress code, but not for women - it only suggested women do not wear too large a hat, in case it obscured someone's view.

So Cooper researched etiquette for a royal wedding, and decided the dress could not show too much cleavage or flesh - Mrs Key will have to wear her coat inside the church to cover her arms.

Meanwhile, The Dress - Kate Middleton's - is due to be copied and on its way to the high street within four hours of its unveiling.

Designers and seamstresses around the world will begin rough sketches for knock-offs which are likely to be on shelves within a week.

The Farmers chain in New Zealand aims to have a recreated gown on display in its Westfield St Lukes store tomorrow morning.

Bridal-wear designer Jane Yeh will spend tonight sewing the replica, which will be a prize in a New Zealand Woman's Weekly reader competition.