The couple have been dating for two years
The son of Prince and Princess Michael of Kent is to marry his actress girlfriend, Kensington Palace has said.
Lord Frederick Windsor, 29, proposed to Sophie Winkleman, 28, on St Valentine's Day and the couple are to wed later this year.
Not a complete stranger to royal life, Miss Winkleman appeared in ITV drama The Palace, and has a recurring role in acclaimed Channel 4 sitcom Peep Show.
Lord Frederick, better known as Freddie, is 31st in line to the throne.
The couple have been dating for two years and have yet to set a wedding date.
Lord Frederick was educated at Eton and Oxford university and now works as a banker for JP Morgan's private banking division.
Miss Winkleman has appeared in a number of TV comedy series including the BBC's Ruddy Hell! It's Harry and Paul.
In The Palace, about a fictional British monarchy, Miss Winkleman played the plotting Princess Eleanor who was enraged when the crown passed to her brother after their father's sudden death. The programme was axed after one series.
A spokesman for Lord Frederick's parents said: "It is with very great pleasure that Prince and Princess Michael of Kent and Mr and Mrs Barry Winkleman announce the engagement of Lord Frederick Windsor to Miss Sophie Winkleman."
Prince and Princess Michael of Kent live at Kensington Palace, which has been their main home since they sold their Gloucestershire country mansion in 2006.
They do not pay rent for the apartment, but Buckingham Palace announced in October that the couple would be charged £120,000 a year from 2010 to remain at the London residence.
Prince Michael is a cousin to both the Queen and the Duke of Edinburgh.
He married his wife, then Baroness Marie-Christine von Reibnitz, in 1978.
She was a Catholic and steadfastly refused to convert to Anglicanism.
Consequently, Prince Michael, who was eighth in line to the throne at the time of his birth, lost his place in the succession.
Their children, however - Lord Frederick and Lady Gabriella Windsor - retain their rights of succession because they are still "in communion with the Anglican Church".