Now into their fifth year as an absurdly attractive couple, Will and Kate, both 24, have lately seemed so snuggly - and Kate so seamlessly ingrained into Will's inner circle of friends and family - that the engagement gossip is getting as hot as a pot of Earl Grey.

Britain's Mail on Sunday even reported last week that Kate has been invited to the Queen's country retreat Sandringham to join the entire Windsor clan for Christmas Day lunch - an unprecedented honor for an unmarried partner of a royal and, if true, said one royal observer, tantamount to an engagement announcement. (Buckingham Palace won't confirm the invitation.)

There is also the 10,000-sq.-ft. neo-Georgian mansion being built by the royal family on part of a 900-acre estate in a village in Herefordshire, which many believe is being readied for Will and Kate.

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