Paintings conservator Alison Smith said she had started first by replacing the linen along the rim and was now re-attaching the loose paint and touching up.
She said the back of the painting was covered in a thick layer of dust and the surface was also very dirty.
“The whole appearance of it was desaturated or washed out with the dirt,” she said.
“It’s always quite rewarding when something’s really dirty, because you like to re-find the colours that it should be.
“The artist has put a waxy layer over the figures so that has protected them from being in a damp environment and just in general from absorbing any more dirt.”
Mrs Worne said she had discovered some more information about the artist Teresa Fuller: “She taught at the Slade School of Art [in London] which is still there, it’s part of a big university now.
“This piece of work was bought at an auction in Greenwich and a lot of Teresa’s art can be found in newspaper articles in the fifties and sixties of churches in that area.”
Ms Smith said Teresa Fuller had “really thought about how to make it last in a church setting”.
