The Royal Albert Hall was filled to capacity this week with 4,300 Christian leaders from over 50 countries for the Holy Trinity Brompton (HTB) Leadership Conference.

Host Nicky Gumbel said, "This is a conference with a purpose. The purpose is to see the transformation of our nation."

Guest speakers included the former Prime Minister Tony Blair who spoke about the dangers of a world without religion during an interview on the first day.

“I think a world without faith would be a world on the path to tragedy and disaster, I really believe that.”

Blair, who converted to Catholicism after he left office in 2007, said “What is the essence of our faith besides all the things we believe, certainly as Christians, about Jesus Christ and his place in our lives? It is also fundamentally a belief that there is something bigger and more important than you, that you are not the only thing that matters, that there is something that is greater and transcendent.”

Rick Warren, the author of The Purpose Driven Life, the fastest-selling book after the Bible, spoke to delegates on Tuesday. He said, "In 1,000 years' time, there will be no USA, no UK, no Microsoft, no Apple, but there will be a church."

"If you want to be successful in leadership you must build your life around integrity, humility and generosity.

"Leadership is like fruit. The best fruit grows in the shade - it ripens slowly."

The conference focussed on four areas of leadership: church, commerce, community and culture.

Judah Smith, 33, pastor of The City Church in Seattle, Washington, with more than 7,000 members was a keynote speaker for the church stream along with Christina Caine, a pastor from Hillsong Church in Sydney.

Caine explained to delegates that her passion for work at the A21 Campaign, which she co-founded, and its fight to see human trafficking abolished, stemmed from her own personal experience of pain and abuse and her subsequent faith in Jesus.

Before she spoke Matt Redman and LZ7 performed their hit song ‘27 million’ which reached number 12 in the iTunes singles chart.

Ken Costa, the former chairman of investment bank Lazard International and Chairman of Alpha International was host of the Commerce stream which heard from Hector Sants, chief executive of the Financial Services Authority, Julian Richer, founder and owner of high street retailer Richer Sounds and Christina Abbott, a director for luxury brand Burberry.

Sir Paul Coleridge, a High Court Judge in the Family division, participated in the community stream where he spoke about the Marriage Foundation, an organisation he launched to champion marriage.

Speakers for the culture stream included freelance journalist, Sam Farmar, who was the first reporter to interview Joseph Kony, ‘the most wanted man in Africa’ and the leader of the Lord's Resistance Army, who in 23 years had never given an interview. Stuart Hazeldine, a UK-based screenwriter and film director who has recently co-written ‘Gods and Kings’, an epic retelling of the life of Moses for Warner Bros, described how his Christian faith influenced the content of his work.

The Bishop of London, the third most senior bishop in the Church of England, also attended and spoke about the experience of preaching at the wedding of the Duke and Duchess of Cambridge in 2011 which was watched by two billion people worldwide.

The conference ended with the crowd reciting the inscription engraved on the frieze that circles the Royal Albert Hall: “Thine O Lord is the greatness and the power and the glory and the victory and the majesty. For all that is in the heaven and in the earth is Thine. The wise and their works are in the hand of God. Glory be to God on high and on earth peace.”