Both Hancock and Church are excited to be joining the judging panel
Charlotte Church, John Partridge and Sheila Hancock have been announced as judges on Andrew Lloyd Webber's latest TV talent show Over the Rainbow.
The new line-up, which replaces Denise Van Outen and John Barrowman, will help decide who should play Dorothy in a new stage production of The Wizard of Oz.
Church called Lord Lloyd-Webber an "icon of the music industry".
Graham Norton will return as host of the Saturday night show, which is set to air in the Spring on BBC One.
Church, who began her career as a classical singer when she was still at school, also launched a brief pop career in 2005.
"I'm so looking forward to working with Andrew - he's an icon of the music industry, and a real hero of mine," she said.
"My career started with Pie Jesu, which was of course written by Andrew, so it feels like I've come full circle."
Actor Partridge is best known for playing Christian Clarke in the BBC One soap EastEnders, but also appeared in Lord Lloyd-Webber's production of Cats in the West End.
"Musical theatre has always been my first love - it's where I began my career - so I'm hugely excited to be joining the panel.
"I can't wait to work with Andrew again and to see what talent the country has to offer. Dorothy is such an iconic role, for so many reasons."
Veteran actress Sheila Hancock has appeared in many TV shows and stage productions.
"I've had an interesting and varied career and I'm so looking forward to working with the panel and Andrew to seek out some fantastic new talent." she said.
"I'm enthusiastic about a TV series which shows the ins and outs of live theatre, and Over the Rainbow will do just that."
Lord Lloyd-Webber said he thought that "each member of the panel brings something new and exciting which will take Over the Rainbow even further than the previous shows".
The series follows on from its successful predecessors which include How Do Solve A Problem Like Maria? and Any Dream Will Do.
The search for Dorothy has already begun, with auditions taking place in cities across the UK.