Churches across London will be anxiously anticipating a special visit this month by a "mystery worshipper" – a specially sent "critic" to assess and evaluate the services at churches. The initiative will see up to 100 "researchers" take to the pews across London’s churches on April 24th and blend in with congregations.

The assessments will later be posted up on the Christian website www.ship-of-fools.com. Inspiration for the project has come from large chain shops such as Asda and Tesco that implement "mystery shopper" schemes that give consumer feedback.

The reports will be presented at a special press event on the opening day of the National Christian Resources Exhibition in May – and churches will be given feedback on warmth of the welcome, length and content of sermon, the music and praise, how comfortable the seats are and even the after service refreshments.

Organisers have said that "Oscar"-type awards will be given for certain categories such as best sermon, music and best overall church.

The editor of the Ship of Fools website, Simon Jenkins said, "Our volunteers go to a church they have never been to before, and experience the service as an outsider. For the church being visited, the only clue is the calling card dropped discreetly into the collection plate, bearing the picture of a masked man in Lone Ranger pose."

The Church "mystery worshipper" project has been going on for seven years now and has covered almost 1,000 churches, but usually individual churches will be targeted by investigators – who go out as far away as Bethlehem. However, the city-wide inspection that is been instigated this time in London is unprecedented, and the organisers have shown their excitement at the project.

Speaking about the project in the past, Jenkins said, "Many churches have taken criticism well. One minister posted the review on a notice board with a 'we must improve' note. Another read the entire report from his pulpit. I also know of a church which took the review on a weekend retreat and the congregation mulled over how it could best answer the criticisms levelled."

The co-editor of the Ship of Fools website, Stephen Goddard said, "Whether they are happy-clappy, bells and smells or rock the flock, we'll have a better picture of what neighbouring churches were like in one 24-hour period."