KATE MIDDLETON’S blue Issa dress sold out within hours of her engagement being announced, with high street retailers quickly offering affordable replicas.

Many retailers openly sold the dress as a “copy”, with one even using the bride-to-be’s “Waity Katie” nickname to describe its waiting list.

Speculation about the wedding dress is now reaching fever pitch, and there is likely to be considerable demand for copycat versions within days of Kate’s arrival at Westminster Abbey on April 29.

Copycat fashion is not new, and consumers have come to expect “the look for less”.

However, in recent years, designers have shown increased willingness to act on infringement, typically, relying on design law for protection.

EC-wide design rights arise automatically. They are attractive to designers because a seasonal, fast-moving item such as a dress rarely justifies the time and cost of a design registration.

Perhaps most importantly, a defence of innocent infringement is not presently available to copyists under EC design law.

In fashion disputes, designers tend to choose their battles carefully. Small-scale copying may not be worth suing over, and the designer may prefer not to draw attention to the replica. Publicity surrounding the item’s resemblance to a higher-end item can often increase its sales.

In many cases, a designer may not take action because sales of its product are not being “diverted” in the classic sense: many of those who purchase copies would not be in a position to buy the original. This will be particularly apparent in a “one-off” purchase such as a wedding dress.

Royal aides have already warned retailers that they should not suggest that a dress or other product is officially endorsed by the couple. For now, it seems that imitation is the sincerest form of flattery.