24 March 1953
Queen Mary, the wife of George V and mother of Edward VIII and George VI, died after a long illness on 24 March 1953. She was 86 and outlived two of her children. She was buried alongside her husband in St George's Chapel, Windsor.
References

BBC News, "Queen Mary dies peacefully after illness", From: BBC News,[Online] Available at:news.bbc.co.uk,[Accessed 11 March 2014].|Royal Central, "Mary ”“ Queen Of Hearts", From: Royal Central,[Online] Available at:www.royalcentral.co.uk,[Accessed 11 March 2014].