Bride-to-be Meghan wished to wear a tiara with emeralds but was refused after its origins could not be established.
The 37-year-old eventually wore a diamond and platinum headpiece selected by the Queen, despite Harry, 34, telling staff previously “what Meghan wants, Meghan gets”.
This instruction to staff is according to reporter Robert Jobson’s new book.
A source told The Sun: “Meghan had her heart set on this tiara with emeralds and Prince Harry hit the roof when they were told it was impossible for her to wear it.
“There was a very heated exchange that prompted the Queen to speak to Harry. She said, ‘Meghan cannot have whatever she wants. She gets what tiara she’s given by me’”.
The Queen warned Harry that Meghan needed to mind how she spoke to staff and to make sure she follows “family protocol”, the book claims.
Her Majesty was also said to have questioned why Meghan needed to wear a veil as it was her second marriage.
It has also emerged that Meghan has clashed with the Duchess of Cambridge about how to treat royal staff.
Kate, 36, has always been “very careful” abut how she speaks to staff compared to Meghan’s Hollywood expectations, added the source.
Meanwhile Meghan and Harry, who are expecting their first child in the spring, are said to have a “game plan” to make sure the baby isn’t spoiled.
The strategy reportedly involves using public transport and doing household chores.
Being part of the royal family means the baby will obviously be born into immense privilege, but there are measures Harry and Meghan can take to keep their kids out of the spotlight.
Harry has been very vocal in the past about his struggles with fame, describing having private and public lives as “a tricky balancing act”.
A royal source told the Sunday Times last month that the couple are considering “the Zara and Peter Philips route”.
This would mean declining royal titles, having independent careers and staying out of the limelight.
The unborn child will be seventh in line to the throne and will not automatically have a royal title unless the Queen intervenes.
Kensington Palace has been approached for comment and declined to comment to The Sun.