Eight recently discovered watercolours by British Romantic poet and artist William Blake are being shown publicly for the first time by Tate Britain in London.

The printed images were first created by Blake, who died in August 1827, to be included in three of his famous illustrated poetry books: The First Book of Urizen, The Book of Thel and The Marriage of Heaven and Hell.

After his death, his wife, Catherine, gave the images to sculptor Frederick Tatham. Then the trail went cold: it's believed the works were passed through private hands, without the knowledge of Blake experts.

They were discovered after someone tried to sell them at an auction earlier in 2007.

The watercolours were originally accompanied by handwritten texts, recently uncovered by Tate researchers in preparation for the show.

"The handwritten words we have now reunited with the pictures are perhaps the most important and newest thing in this show," curator Robin Hamlyn told the Guardian newspaper.

"They give people a better idea of the way Blake was thinking at this time and are a key to his imagination."

Several of the illustrations show the struggles of Urizen, Blake's god of reason.

"He seems to have … boiled things down to almost a series of aphorisms," notes Hamlyn.

In one image, Urizen is an old man in the woods facing a fierce lion and is accompanied by the phrase: "Fearless though in pain I travel on."

The Blake exhibit, I still go on/Till the Heavens & Earth are Gone, runs until June 2008. It also features a rare copy of the poet's first book of verse and prose, Poetical Sketches, and is marked with the writer's own corrections to some of the lines.