The document, signed by the 92-year-old monarch earlier, incorporates some symbols of America onto traditional vellum to represent the bride's origins. The first six people in line to the British throne must seek the Queen's formal approval to marry, without which Prince Harry the sixth in line would have been disqualified from the line of succession.
"Now know ye that we have consented and do by these presents signify our consent to the contracting of matrimony between our most dearly beloved grandson Prince Henry Charles Albert David of Wales KCVO and Rachel Meghan Markle," the instrument reads.
The Instrument of Consent began after the UK's Royal Marriages Act of 1772. It required descendants of King George II to get the sovereign's consent before they wed, otherwise their marriages would be invalid. It reportedly came in after King George III's younger brother, the Duke of Cumberland, secretly married Lady Anne Horton, deemed to be the highly disreputable widow of a commoner.
The law was replaced with the more recent Succession to the Crown Act 2013, which allows a member of the British royal family to marry a Roman Catholic but a Roman Catholic cannot become King or Queen. The act also removed male bias from the line of succession.
With the birth of Prince Louis, the Duke and Duchess of Cambridge's third child last month, Prince Harry is now sixth-in-line to the British throne after his father Prince Charles, brother Prince William, and nephew Prince George and niece Princess Charlotte.
Meanwhile, wedding preparations are on in full swing with thousands of royal fans and well-wishers expected to descend upon the town of Windsor next weekend.
Kensington Palace has announced that American bishop Most Reverend Michael Curry, the head of the Episcopal Church, will be part of the wedding ceremony next Saturday. The choice of an American pastor marks a break from custom as traditionally addresses at royal weddings are given by senior clergy from the Church of England.
Archbishop of Canterbury Justin Welby, the leader of the Church of England and spiritual head of the Anglican Communion, will conduct the wedding service. He also presided over Markle's baptism as an Anglican at a ceremony at Kensington Palace in March.
Harry, 33, and Markle, 36, are set for a very different kind of royal wedding, asking guests to consider donations to their chosen charities in place of showering them with wedding gifts. Among their chosen charities is the Myna Mahila Foundation, an organisation that works with women in Mumbai's slums to provide them with employment opportunities.
However, there are some reports that they also have a secret wedding list for gifts from Soho House the exclusive London club where the couple met on a blind date. That list is only for their inner circle of friends and family to choose a present from the club chain's high-end catalogue.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)