Books like The O'Sullivan Twins
Enid Blyton
The O'Sullivan Twins is 183 pages, about 3 hours 21 minutes at 250 words a minute.
12 books to read next
How long each takes
The Third Form at St Clare's 2.8 h 
The Sixth Form at St Clare's 2.9 h 
The Vanishing Stair 7.1 h 
Charlie Bone and the Time Twister 7.0 h 
The It Girl 4.8 h 
Big Trouble 5.0 h 
The Butterfly Lion 2.3 h 
Silver 5.7 h 
Notorious 5.1 h 
Reckless 4.4 h 
The Lost Twin 5.4 h 
Whispers in the Walls 5.3 h Bar height shows length. Estimated at 250 words a minute.