Details of the letter come after Princess Beatrice has faced a string of setbacks since announcing her engagement to her property developer beau in September 2019.
After revelations of her father Prince Andrew's involvement with disgraced financier Jeffrey Epstein, as well as Prince Harry and Meghan Markle's departure from royal life, Beatrice's wedding plans have been delayed and their wedding date is yet to be officially announced.
Now it is being reported that Queen Elizabeth is giving her granddaughter a "boost in morale" by offering to host the lavish reception at Buckingham Palace.
One friend revealed to Daily Mail: "Bea was delighted and very grateful to accept."
"It was a really special gesture as it will be the first wedding celebration at Buckingham Palace since William and Catherine's in 2011."
While Buckingham Palace will host the lavish wedding reception, it looks like Beatrice will choose a London venue for her actual ceremony, the exact location and date of which are yet to be confirmed.
This is in contrast to her sister Princess Eugenie, who married Jack Brooksbank at St George's Chapel in Windsor in 2018.
It was initially reported that the Bea and Edo consulted with Her Majesty and agreed on a June wedding date, however this is still to be formally announced.
"Bea and Edo will finally announce their wedding date in the second week of January,” an insider told the Mail on Sunday at the time.
"The date has been described as 'early summer', just before the summer social season kicks off."
However the recent announcement by the Duke and Duchess of Sussex has reportedly further delayed their wedding day announcement.
The daughter of Sarah 'Fergie' Ferguson revealed details of her engagement in September 2019.
“We are extremely happy to be able to share the news of our recent engagement," they said.
“We are both so excited to be embarking on this life adventure together and can’t wait to be married.
“We share so many similar interests and values and we know this will stand us in great stead for the years ahead, full of love and happiness.”