IT HAS been an exciting time for arts books, what with Jane Renouf's Lake Artists Centenary reaching the book shelves this year and the Walter Sickert catalogue to go with the artist's fantastic Human Canvas exhibition at Abbot Hall.

So you can imagine my euphoric state when Chris Wadsworth, owner of Cockermouth's Castlegate House Gallery, rang me to say she'd put together a book and an exhibition about some letters Workington-born artist Percy Kelly had written.

I'm partial to the late Percy's work and rate Mary Burkett's definitive biography (with Valerie Rickerby) as one of my favourites.

And in Mary and Valerie's book they mention how letters were Percy's lifeline.

The Painted Letters exhibition at Castlegate runs until October 6 and charts the extraordinary story of the friendship between Percy Kelly, an artist who was originally a postal worker in west Cumbria, and Joan David, a retired scientist and art collector who lived in Kendal. During the Second World War Joan had studied for her MSc at the Freshwater Biological Association's laboratories at Wray Castle, near Ambleside, and had been introduced to Percy by Mary Burkett.

It must have been quite staggering to receive, as Joan did, such personalised and exquisite work painted on envelopes and letters.

It must have been entertaining for the postman too.

Percy would paint a watercolour on an A3 or A4 sheet and then write his letter, filling the spaces with words, then pop it into an equally beautifully-created envelope.

Though Percy and Joan only met five times during a ten-year period, the letters follow the hopes and concerns of a talented artist but seemingly a tortured soul.

The letters are full of Percy's vivid memories. They deal with his flight from Cumbria in 1971, into a self-imposed exile first in Wales and then in Norfolk, slipping into a lonely and poverty-stricken old age.

His first letter to Joan was in January 1983 just before his second wife left him.

After, he became more and more obsessive and the letters tracked his problems as he tried to cope with his transvestism, depression and loneliness.

Joan gave him a lot of moral and financial support and even persuaded him to have a selling exhibition at her friend's house, near Windermere in 1984, to settle his debts.

They wrote to each other every week until his death in 1993 aged 76.

Joan died in January 2000 and last year her son and daughter decided to give Chris - their mother's close friend - access to the letters.

Chris couldn't believe what she discovered. "I was thrilled to be asked by Joan's family to go to Kendal and open her large oak chest in which she kept all her letters from Percy Kelly," she told me.

"Joan was a close friend who died four years ago and although she had shown me quite a few of her letters, I was quite unprepared for the sheer volume of it all. There were well over 1,000 letters sent over a period of ten years and some were over 30 pages long.

"I was awestruck and didn't want to dwell on his personal difficulties but concentrate on his art.

"It took me three months to just read all the letters and then I spent the winter break editing them for the book.

"Joan's family decided that they should be exhibited rather than lying in a chest - and this is the result."

Chris says the letters are spectacular and unique each a painting in its own right. Many are beautifully framed, looking fabulous on display in the three large exhibition rooms at Castlegate.

More than 80 pieces, plus artefacts such as Percy's pipe, are on show, and a 15-minute video including extracts from an interview with Joan that Chris did years ago.

Leafing through the book you can imagine the delight with which the letters were received - decorated envelopes and enclosures of little paintings, drawings, puzzles and sketches: the landscape, seasons, weather, animal and plant life keenly observed in detail through the eyes of a very sensitive artist.

Although Chris felt privileged to be able to put the exhibition together, sifting through the letters was no easy task.

"It's been hard work, but this sort of opportunity only comes around once in a lifetime."

Chris has staged several selling exhibitions of Kelly's work over the years and Painted Letters was "just the icing on the cake."

"You wonder what will turn up next," she said.

The Percy Kelly story just runs and runs.

l The full-colour 136-page The Painted Letters of Percy Kelly hardback is available from the gallery and at Kendal's Ottakers and Henry Roberts bookstores as well as Kirkland Books.

Castlegate is open daily 10.30am-5pm, closed Thursdays. Sundays 2pm-5pm. Contact 01900-822149 for further details.