Prince Edward celebrated the opening of a new branch of Christian children's charity, Scripture Union (SU).
The organisation opened a new office in Fox Milne, Milton Keynes.
The Earl of Wessex was given a tour of SU's new Headquarters and its facilities, unveiling a plaque to mark the special occasion.
On unveiling the plaque The Earl of Wessex said, "Thank you very much indeed for inviting me to come and visit your brand new offices and I'm delighted the move has been a positive one for what you're trying to do".
The Earl also got an update about the organisation's new campaign called, 95.
It aims to reach the 95 per cent children in England and Wales who aren't in church regularly.
Through the campaign, the charity look to resource, train, equip and empower thousands of churches across the country to increase and improve their outreach work with children and young people.
The National Director of SU England and Wales, Tim Hastes-Smith, tells Premier the charity will use 150 new mission initiatives.
He said: "They could be digital models; they could be quite traditional models like sort of missions in the park or on the beach.
"They could be new ways of doing sports, an activity, adopting a mugger in a town centre and working with sports and young people and suing that as ab opportunity to make Christ's love known.
During his speech, Prince Edward said: "I wish you the best of luck, not only for your 150th anniversary, but also the challenge that you're trying to do in reaching that 95 per cent.
"I have great appreciation for all of the Scripture Union team, for the work that you do and continue to do."
Hastie-Smith said: "We hugely enjoyed welcoming The Earl of Wessex to Milton Keynes today to officially open our new National office.
"An old friend of Scripture Union, HRH's passion for work with children and young people, rooted in his leadership of The Duke of Edinburgh's Award scheme, was infectious and he loved meeting both our staff and some of the teenagers we work with. We were encouraged that he left excited by SU's great vision for the future."