The archbishop of Canterbury will exchange Royal wedding celebrations for a youth evangelism event next week as hundreds of thousands of Christians mark 11 days of prayer around the world.

Justin Welby will officiate at Prince Harry and Meghan Markle's wedding on May 19 and is a guest at the lunchtime reception hosted by the Queen in St George's Hall afterwards.

But while the nation parties into the night, and a select number of the couple's closest friends and family are invited to an after-party hosted by Prince Charles at Frogmore House, the archbishop will head straight off to preach at a youth evangelism event an hour away in St Albans.

The gathering is part of Thy Kingdom Come, a prayer and evangelism initiative that has swept around the world since it was launched two years ago by Welby and John Sentamu, the archbishop of York.

Now in its third year and involving hundreds of thousands of Christians in more than 85 countries around the world, Thy Kingdom Come has spread to all the major Christian denominations.

From Fiji to Finland Anglicans, Methodists, Baptists, Catholics and Pentecostals will join the initiative which has become a major feature in Welby's annual programme.

Neither Lambeth Palace nor Kensington Palace would comment as to whether the archbishop had received one of the 200 invites to the royal wedding evening party. It would not be a surprise given the close relationship he has built with the couple. But such is Welby's focus on Thy Kingdom Come, it is questionable whether he would have turned down preaching in order to attend the exclusive celebration.

'I cannot remember in my life anything that I've been involved in where I have sensed so clearly the work of the Spirit,' Welby has said of the initiative.

This year thousands of churches around the world are hosting prayer and evangelism events in the 11 days between Ascension and Pentecost — the Anglican festivals marking Jesus' departure for heaven after his resurrection and the arrival of the holy spirit on his disciples.

Although Thy Kingdom Come was started by Welby, it has received backing from the Catholic head in the UK, Cardinal Vincent Nichols, the Methodist head Gareth Powell and the Coptic head, Bishop Angaelos.

Cardinal Nichols said: 'We do this, with a deep realisation that our world is not right. But we do it with a profound hope, profound trust in the promises of Jesus, that His Kingdom will come and in that trust and hope we pray.'

Powell said: 'Methodist participation in the Thy Kingdom Come prayer initiative enables us to be very clear about our desire to see the reign of God's love in the world today. Between 10-20 May 2018, we have a remarkable opportunity to remind ourselves, that we take place with all God's people, in sharing in the heartfelt prayer "Thy Kingdom Come".'

Bishop Angaelos said: 'This initiative Thy Kingdom Come is something I am so blessed to have been part of for two years and it is really a time for us to stand together and pray together to put into words, into chant, into hymns - into whatever means we desire - our petitions before God - for ourselves, for our churches, for our communities and our world.'