In the 1950/60's The Childrens Book Club published three William books which had the original illustrations inside. However the front covers and spines were certainly NOT original !!
William& the Moon Rocket Front Cover (CBC)
William & the Moon Rocket (CBC) Spine
William & the Space Animal Front Cover (CBC)
William & the Space Animal Spine (CBC
William's Treasure Trove Front Cover (CBC)
William's Treasure Trove Spine (CBC)