Singers from six choirs from across Hertfordshire joined together to sing with a famous singing group.
The choirs Amersham A Cappella, Carillon, Jubilate, Lemon Tuesday, Singing Circle and Ursa Minor came together to form Ursula Major in a performance at the Radlett Centre.
The groups accompanied Blake, nicknamed "the opera hunks", who regularly appear on TV, at the Wembley Stadium and the Royal Albert Hall and have also sung for the Queen.
The choirs ranged from barbershop to classical, teenagers to adults with members having a wide range of experience.
Ursula Major accompanied Blake in five songs - Nessum Dorma, You raise me up, Halleluja, Up where we belong before, and Jerusalem.
They also opened the second half with a solo item, Adiemus, accompanied by percussion and recorder played by younger members of the choirs.
One of the group members commented: "It was lovely to meet other singers, perform with Blake and sing music we do not usually have the opportunity to learn."