Queen Elizabeth II
Queen Elizabeth II waves as she stands on the balcony of Liverpool Town Hall in Liverpool, Britain, June 22, 2016. REUTERS/Phil Noble

At 90 years of age, Queen Elizabeth II is battling “heavy cold” triggering concern among Britons over her health. Although Princess Anne said that her mother is feeling “better,” the queen’s health scare had led to speculation whether she will retire from her royal duties.

Succession to the British throne is established by descent, gender (for those born before October 2011), legitimacy and religion. After the queen, the throne will be passed on to her son Prince Charles. But his wife Camilla, Duchess of Cornwall, is unlikely to become the next queen of England due to her troubled past with Britons over her relationship with Charles while he was still married to Princess Diana.

Duchess of Cornwall Camilla and Kate Middleton
Duchess of Cornwall Camilla and Duchess of Cambridge Kate Middleton travel in a carriage to Horseguards Parade for the annual Trooping the Colour ceremony in central London, June 11, 2016. Reuters/Toby Melville

Prince William, the Duke of Cambridge, follows his father in line to the throne and his wife Duchess of Cambridge Kate Middleton is likely to hold the ceremonial title of queen without having any claim to the throne. However, their second child — daughter Princess Charlotte — may take the throne to become England’s queen after her elder brother Prince George dies or abdicates before fathering an heir or if something happens to his heir.

William’s brother Prince Harry is fifth in line to the throne following George and Charlotte.

The queen has four children — Prince Charles, Princess Anne, Prince Andrew and Prince Edward. In 2009, her husband Prince Philip, the Duke of Edinburgh, became the longest serving British consort.

Prince Andrew, the second son and third child of Elizabeth and Philip, has two daughters — Princess Beatrice and Princess Eugenie — with his then-wife Sarah Ferguson, the Duchess of York. His marriage with Sarah was dissolved in 1996.

After Andrew is the queen third’s son Edward who holds the title Earl of Wessex. He has two children with his wife Sophie Rhys-Jones — Lady Louise and James, Viscount Severn.

The queen’s only daughter Anne, who is the Princess Royal, has been married twice and is a mother to two children — Peter and Zara — from her first marriage to Captain Mark Phillips. Both her children do not hold royal titles because they are descendants of the female line and because Mark Phillips declined the offer of an earldom when he married Princess Anne.

Queen Elizabeth II
Queen Elizabeth views a portrait of herself by British artist Henry Ward, commissioned to mark her six decades of patronage to the British Red Cross, at Windsor Castle, Oct. 14, 2016. REUTERS/Dominic Lipinski/Pool

The queen’s eldest grandchild and Anne’s son Peter Phillips has two daughters — Savannah and Isla — with wife Autumn Kelly.

Anne’s daughter Zara Tindall is a successful athlete and has won silver medal at the London Olympics in 2012. She is the wife of former rugby player Mike Tindall and the two are parents to a daughter, Mia Grace.

Following is the current line of succession:

1. Prince of Wales, Charles

2. The Duke of Cambridge, Prince William

3. Prince George of Cambridge

4. Princess Charlotte of Cambridge

5. Prince Harry of Wales

6. Duke of York, Prince Andrew

7. Princess Beatrice of York

8. Princess Eugenie of York

9. Earl of Wessex, Prince Edward

10. James, Viscount Severn, Edward’s son

11. Lady Louise Windsor, Edward’s daughter

12. Anne, Princess Royal

13. Peter Phillips, Anne’s son

14. Savannah Phillips, Anne’s granddaughter

15. Isla Phillips, Anne’s granddaughter

16. Zara Tindall, Anne’s daughter