I'm taking my earlier predictions of "that there are 26 Diane Redmond books" back, as I've done some internet searching, and I don't think there are that many. I've decided to compile a list of the known books and their order. If you can help out, that would be great since I don't own all of these books! Some have very similar titles and are a little confusing and since I don't own them physically it's hard to tell where they fit in.
1. "Fiver's dream" Follows episode 1.
By Diane Redmond.
Covers episode 1 from the beginning up until after the rabbits escape the dog by swimming the river.
2. "Pipkin makes a friend". Follows episode 1.
By Diane Redmond.
Continues from the last book and episode 1. The rabbits take shelter in the field of tall plants, rescue and befriend Keehar and Hannah, and find a home on top of the down.
3. "Bigwig learns a lesson" Follows episode 3, however the first page mentions Holly arriving on the down, which happened in episode 2.
By Diane Redmond.
Holly takes Hazel, Bigwig and Fiver to Cowslips warren to find Bluebell. Bigwig gets caught in the snare, and the rabbits bring Strawberry back to the down.
4. "Hazel the Brave." Follows episode 5.
By Diane Redmond.
Hazel, Fiver and Bigwig go into Efrafa. Primrose and Blackavar are introduced. Hazel and Fiver walk away from Efrafa unharmed.
5. "Hazel raids the farm." Follows episode 6.
By Diane Redmond.
Follows the episode. Hazel tries to free the farm rabbits, but is shot by the farmer. He decides that he must go back to Efrafa and rescue Primrose.
6. "Challenge to Efrafa." Follows episode 7
I DO NOT OWN THIS BOOK, SO I AM UNABLE TO GIVE A COMPLETE GUIDE TO IT.
7. "Primrose's great escape." Follows episode 8.
By Diane Redmond.
Now that Bigwig is part of Woundwort's army, he is able to help Primrose and Blackavar escape. Woundwort gives chase, but the rabbits escape in a boat.
8. "Fiver's bad luck." Follows episode 9
By Diane Redmond.
Primrose is happy living at the down, but Fiver has a vision about her old warren Redstone. Primrose travels with Hazel to Redstone to see if Fiver's vision is true. The weasel returns to the down. Hazel confesses his love to Primrose. Captain Broom is introduced and now lives on the down. No mention that Hazel is going to be a father. By Diane Redmond.
9. "Friend and foe" Episode 10, Episode 12.
By Judy Allen.
First chapter has Dandelion telling the Rowsbry Woof story from episode 10. The rest of the book follows the events of episode 12.
10. "Hawkbit's Discovery / The Hidden World"
Hawbit's Discovery by Diane Redmond. The Hidden World by Judy Allen.
I DO NOT OWN THIS BOOK AND AM UNABLE TO GIVE ACCURATE INFORMATION.
Treasuries / Collections:
Books 1 - 4 are complied in a hardback book; "The Watership Down treasury." Confirms the places of the first 4 books.
"The collection" contains 4 books in a cardboard slipcase. The books are "Fiver's bad luck, "Hazel raids the farm," "Primrose's great escape" and "Hawkbit's discovery."
Spin off's:
"Pipkin's Rainbow."
Pipkin teaches you about the colours of the rainbow.
"Count with Fiver."
Fiver teaches you to count in rhyme.
Books I know of but cannot place in the timeline or am unsure of it's place in the timeline:
"Rabbits in Danger"
"We need more rabbits!"
"Campion and the slither thing."
"Escape to the hills."
"Pipkin in danger!"
"Rabbit's betrayed."
"Prisoner of Efrafa."
Episodes that are not covered by a book:
Episode 2: "Home on the Down."
Episode 4: "Strawberry Fayre."
Episode 10: "A Tale of a mouse." [Only the Rowsby story is covered]
List will be added to as the timeline progresses
Notes:
"We need more rabbits!" suggests that Hazel looks for more rabbits, which could be that he raids the farm, or discovers Efrafa. Need to read to find out.
"Escape to the hills" suggests that the rabbits move to the hills. Could be that it covers the first few episodes. Need to read to find out.
"Rabbits in danger" Could be the second episode with the weasel.
"Rabbit's betrayed" It is possible that this covers the episodes leading up to and including the eventual departure of Hickory and Marigold from Cowslip's Warren.
Differences in stories by author
Books by Diane Redmond are meant to be a for a younger audience as they are simple and easy to read. They are meant for little kids who are unable to read properly yet or are just starting out reading "lengthy" stories.
Books by Judy Allen are "for children who are ready to read on their own." They are paperbacks, have chapters in them, include a map of the Watership world, provides a little information on the characters and has possibly new/unused line art as illustrations. There is also a glossary.