Growing press speculation across the world.
Inline to be King and Queen of Australia
The announcement of their engagement is said to be imminent. And the pair, both 28, were inseparable yesterday at the marriage of their friends Harry Meade and Rosemary Bradford in Northleach, UK
Reports that a plaster mould has been created from which the coins will be struck in gold and silver were not denied by the Mint when approached yesterday after a Sunday newspaper printed alleged details of the plans.
A source told the Mail on Sunday that he had seen the mould at the Mint's plant in Llantrisant, south Wales.
Dave Knight, head of commemorative coin at the Mint, said: "Like most businesses, we look forward and plan ahead for potential opportunities.
"Were Prince William and Kate Middleton to announce their engagement, we would certainly like to produce a commemorative coin to mark this happy occasion.
Speculation is mounting that Prince William and Kate Middleton will marry next year – and could become the Duke and Duchess of Cambridge.
The couple’s formal engagement will be announced early in 2011 followed by a summer wedding, according to reports from royal insiders in national newspapers.
The day could also be declared a national holiday. The couple, both 28, have been together for more than eight years.
On the morning of the big day the Queen is likely to announce new titles for the couple – possibly the Duke and Duchess of Cambridge, it has been reported by a royal source.
Speculation over the wedding has been mounting for months. Bookmakers William Hill stopped taking bets on a 2011 wedding and will now only give odds on the month. William and Kate met at St Andrews University in 2001.