The act says: "Succession to the Crown not to depend on gender: In determining the succession to the Crown, the gender of a person born after 28 October 2011 does not give that person, or that person's descendants, precedence over any other person (whenever born)."
The same act also meant that members of the Royal family who marry a Catholic will no longer be disqualified.
Last month Clarence House fuelled speculation that the Duchess of Cornwall could yet be made Queen after deleting all references saying she will be styled as "Princess Consort" when Prince Charles becomes King from his official website.
The heir to the throne's office has quietly taken down a statement, made before the couple got married in 2005, in which they said it is "intended The Duchess will be known as HRH The Princess Consort when The Prince of Wales accedes to the throne."
It was also removed from her personal biography.
Clarence House officials insisted that the statement had been removed some time ago from their "Frequently Asked Questions" segment because the public was no longer interested in the issue.
A spokesman said: "This is one question that Clarence House has not been asked by the public for some time, which is why it no longer features."