The Queen will celebrate her 91^st birthday in private today with her official birthday celebrations held in June.

The King's Troop Royal Horse Artillery will fire 41 volleys in her honour at midday in Hyde Park. A further 62 volleys will be fired at the Tower of London an hour later.

Her Majesty has been stalwart in her faith since she committed herself to a life of service under God in a radio broadcast on her 21^st birthday.

On this day in 1947 she said: 'I declare before you all that my whole life, whether it be long or short, shall be devoted to your service and the service of our great imperial family to which we all belong.

'But I shall not have strength to carry out this resolution alone unless you join it with me, as I now invite you to do: I know that your support will be unfailingly given.

'God help me to make good my vow, and God bless all of you who are willing to share it.'

Here are nine quotes from Her Majesty which demonstrate her Christian faith, drawn from the Christmas messages in which she speaks directly to the nation.  

1. 'It is true that the world has had to confront moments of darkness this year, but the Gospel of John contains a verse of great hope, often read at Christmas carol services: "The light shines in the darkness, and the darkness has not overcome it"... Despite being displaced and persecuted throughout his short life, Christ's unchanging message was not one of revenge or violence but simply that we should love one another' (Christmas message, 2015). 

2. 'For me, the life of Jesus Christ, the Prince of Peace, whose birth we celebrate today, is an inspiration and an anchor in my life. A role model of reconciliation and forgiveness, he stretched out his hands in love, acceptance and healing. Christ's example has taught me to seek to respect and value all people, of whatever faith or none' (Christmas message, 2014). 

3. 'For Christians, as for all people of faith, reflection, meditation and prayer help us to renew ourselves in God's love, as we strive daily to become better people. The Christmas message shows us that this love is for everyone. There is no one beyond its reach' (Christmas message, 2013).

4. 'This is the time of year when we remember that God sent his only son 'to serve, not to be served'. He restored love and service to the centre of our lives in the person of Jesus Christ. It is my prayer this Christmas Day that his example and teaching will continue to bring people together to give the best of themselves in the service of others. The carol, In The Bleak Midwinter, ends by asking a question of all of us who know the Christmas story, of how God gave himself to us in humble service: 'What can I give him, poor as I am? If I were a shepherd, I would bring a lamb; if I were a wise man, I would do my part'. The carol gives the answer: 'Yet what I can I give him – give my heart'' (Christmas message, 2012).

5. 'Although we are capable of great acts of kindness, history teaches us that we sometimes need saving from ourselves – from our recklessness or our greed. God sent into the world a unique person – neither a philosopher nor a general, important though they are, but a Saviour, with the power to forgive... It is my prayer that on this Christmas day we might all find room in our lives for the message of the angels and for the love of God through Christ our Lord' (Christmas message, 2011).

6. 'For me, as a Christian, one of the most important of these teachings is contained in the parable of the Good Samaritan, when Jesus answers the question, 'Who is my neighbour?' It is a timeless story of a victim of a mugging who was ignored by his own countrymen but helped by a foreigner – and a despised foreigner at that. The implication drawn by Jesus is clear. Everyone is our neighbour, no matter what race, creed or colour. The need to look after a fellow human being is far more important than any cultural or religious differences' (Christmas message, 2004).

7. 'To many of us our beliefs are of fundamental importance. For me the teachings of Christ and my own personal accountability before God provide a framework in which I try to lead my life. I, like so many of you, have drawn great comfort in difficult times from Christ's words and example' (Christmas message, 2000).

8. 'I know just how much I rely on my own faith to guide me through the good times and the bad. Each day is a new beginning, I know that the only way to live my life is to try to do what is right, to take the long view, to give of my best in all that the day brings, and to put my trust in God. Like others of you who draw inspiration from your own faith, I draw strength from the message of hope in the Christian gospel' (Christmas message, 2002).