Meghan Markle, 36, and Prince Harry, 33, are getting increasingly serious, with the actress believed to have relocated to London to be closer to her boyfriend.
Royal watchers are certain an engagement announcement will come later this year, with a wedding then following in Spring 2018.
The couple would have the choice of any wedding venue in the UK they wanted – and there is one in particular they are more likely to choose.
Harry has been said to want a more low-key, private affair by friends, so a London wedding is unlikely.
He would probably try and emulate the country nuptials of Pippa Middleton, who managed to keep most of her wedding to James Matthews earlier this year private. Meghan attended the evening reception but was not photographed by a single camera on her way in.
If so, royal venue The Sandringham Estate in Norfolk would be an obvious choice.
Harry has spent many happy occasions in his grandmother’s Sandringham home, and is expected to return again this Christmas.
His brother, Prince William, lives in nearby Anmer Hall with Kate Middleton and their children.
As well as a church on site, there is the Sandringham restaurant which is available for weddings and events, so an experienced team is already in place to cope with any celebrations.
There is also space for a marquee, which is described on the website as “secluded and private”.
Many Britons are quietly wishing for a wedding between the couple in the hopes it will lead to a Bank Holiday for the UK.
There was a national holiday for Prince William and Kate Middleton’s wedding in 2010.
But now a Palace insider has revealed there will be no such joy for Britons this time around.
This is because the couple are said to be keen for a more private wedding, and plan to shun the option of getting married in Westminster Abbey.
The source told the Daily Star: “Pomp and pageantry is the last thing he would want.”
However the source claimed Windsor Castle is a potential venue, and did not mention Sandringham as a contender.