Royal coup for Aussie designers Zimmermann

While plenty of fans at the Royal Easter Show are cheering the royals, the Duchess of Cambridge is waving the flag for Aussie fashion designers.

Kate is wearing Zimmermann's $495 white/cream cotton lace "Roamer" day dress - a perfect fit for a sunny autumn day at the show.

The dress won't be in stores until June, and is bound to sell out.

The sisters behind the brand - Nicole and Simone Zimmermann - have come a long way since they started out selling clothes at Sydney's Paddington Markets in the 1990s.

Last week, they were awarded the seventh Australian Fashion Laureate title at Australian Fashion Week, and now the "Kate effect" is certain to boost their profile even further.

Just to prove the Kate effect, the Zimmermann website froze as soon as word emerged that she was wearing their design.