David Cameron has led tributes to Queen Elizabeth II as the "brilliant" British monarch celebrates her 90th birthday. The prime minister described the head of state as a "rock of strength" and thanked her for her public service.

"On behalf of the whole country, I want to wish Her Majesty the Queen a very special 90th birthday. Her Majesty has devoted her entire life to the service of others, representing our country, and carrying out all of her duties with extraordinary grace and humility," Cameron said.

"Rarely has anyone in public life service for so long, served so brilliantly, worked so hard, and brought so many people together.

" And in this modern Elizabethan era, in which so much around her has changed, Her Majesty has been steadfast, a rock of strength for our nation, for our Commonwealth, and on so many occasions, for the whole world.

"She is our Queen and we could not be more proud of her. Happy Birthday You Majesty, and long may you continue to reign over us all."

The Queen is expected to carry out a walkabout around Windsor, where she will unveil a plaque, and light a beacon in the evening to celebrate the landmark birthday. Gun salutes will also be held across the UK, while the Houses of Parliament will be illuminated at night.

Incredible archive video charts life of Queen Elizabeth IIIBTimes UK

The monarch, who has been the UK's head of state since 1952, will enjoy more celebrations in June for her official birthday. Prince Charles, the second-in-line to the throne, made his own Shakespearean tribute to his mother, reading an extract from Henry VIII.

"She shall be, to the happiness of England, an aged princess; many days shall see her, and yet no day without a deed to crown it," he declared during a broadcast for the BBC.

The leader of the Her Majesty's Opposition, Labour's Jeremy Corbyn, will pay tribute to the Queen during a speech in the House of Commons. A spokesman for Corbyn told IBTimes UK that the party will also release a social media message from the left-winger.