The store says it has no "inside" information about the couple

The chain-store's designs range from traditional china plates and thimbles to a mouse mat and a range of Will and Kate-shaped pick and mix sweets.

The retailer's bosses said they wanted to be prepared in case the couple announced they intended to marry.

But a spokesman stressed that the chain had no "inside information".

Some of the early designs consist of pictures of the couple with a gilt edge.

Beneath is the message: "Celebrating the Royal marriage of William and Kate," with a space left for the date.

Planned celebrations

Marketing director Stephen Robertson said Woolworths did not want to be surprised by a sudden announcement of the couple's engagement.

He told the Daily Mirror: "We plan to be ready. This will allow our customers to celebrate a royal wedding in style.

"There was a massive demand for products when Charles and Camilla got married.

"But because of their short engagement we didn't have enough time to design, manufacture and retail products. This time we'll be ready."

The market for spin-off products from any new royal wedding could be worth �10m, according to the retailer.

There has been a steady build-up of speculation that Prince William and Ms Middleton will soon be announcing their engagement.

William Hill slashed the odds on an engagement before the end of 2006 to 3-1 in December. The couple, both aged 24, met at St Andrews University, Fife, in 2001.

Their first public appearance together was three years later on a skiing holiday.