It's been a jolly long time since their last adventure.

But the Famous Five are back  -  and setting out to solve their first mystery in 45 years.

Julian, Dick, Anne, George and Timmy the dog return to the trail as part of a plan to revisit some of Enid Blyton's best-loved characters, her estate has announced.

The latest Famous Five story is among 20 books based on Blyton's characters to be published over the next two years.

And, as ever, there's a case for the gang to crack. Now grown-up, the friends go back to the Mystery Of The Royal Dragon Of Siam, which apparently flummoxed them as children.

The Famous Five are back to solve their first mystery in 45 years

Set in 1959, it did not feature in the 21 adventures published between 1942 and 1963. That year was the only one in which a book was not released.

A mystery and survival guide rolled into one, the book, published next month, is 'packed full of stolen treasure, problem solving, traps and traitors', said publisher Chorion.

'Included are their personal diary pages and all the clues they collected about the mystery at the time.

'As the Famous Five tell their story they also share their guide to solving mysteries and adventuring in the great outdoors with tips on cracking codes, using a compass, building an escape raft and camping.'

If the gang weren't your favourite characters, there's no need to panic, old thing. Adventures involving the Faraway Tree and Malory Towers are also in the offing.

Chorion, which own the rights to Blyton's characters, says the stories will 'remain true to Blyton's classic storytelling style and values'.

The Faraway Tree returns next month, with a spin-off story, The Enchanted World.

Written by Elise Allen, better known for screenplays than children's literature, it focuses on Silky The Fairy, and is to be told in a modern style.

The story will follow the fairy and her four new friends on a mission to save the tree from a troll.

The author of the Famous Five book is being kept a closely guarded secret.

Tony Summerfield, organiser of the Enid Blyton Society, said: 'When I asked, I was told it was written by the Famous Five themselves.'