Prime Minister David Cameron said:
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 her duties with extraordinary grace and humility.
Rarely has anyone in public life served 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 Your Majesty, and long may you continue to reign over us all.