Prince Harry and Meghan Markle may have to wait a couple more months to find out if they can trademark their Sussex Royal brand after a doctor from Australia filed a complaint against it.

Documents filed at the Government's Intellectual Property Office reveal that a certain Benjamin Worcester of Victoria, Australia, who studied medicine at University College London, has filed a complaint against the Duke and Duchess of Sussex's trademark registration. Prince Harry and Meghan Markle would have to build a legal case, if necessary, against the complaint.

Worcester, who worked as a doctor in the NHS in London between 2011 and 2014, filed the "notice of threatened opposition" on Tuesday. There are no details as of yet on why he filed the complaint.

However, the opposition puts a dent in the royal couple's plans to trademark their Sussex Royal brand, so they can use it for marketing and charity. Prince Harry and Meghan Markle plan to use their social media handle to sell merchandise and launch their charity foundation.

Now, the Duke and Duchess of Sussex have to wait until March 20 to find out if they can trademark Sussex Royal. According to Hello Magazine, the period of opposition was supposed to end on February 20. Prince Harry and Meghan Markle plan to trademark Sussex Royal to support their intent to live a financially independent life.

News of the trademark opposition comes after Queen Elizabeth II officially stripped the Sussexes of their duties as senior members of the Royal Family. They are no longer allowed to represent the monarch when they do public engagements for the charities and organisations they personally support. It comes in the wake of Prince Harry and Meghan Markle's decision to spend most of their time in Canada after their royal exit.

Prince Harry and Meghan Markle
Britain's Duke and Duchess of Sussex Prince Harry and Meghan Markle Photo: POOL / DANIEL LEAL-OLIVAS