Abstract: A knife for trimming wallpaper has two tapered body parts 8 and 9 between which is held a tipped cutting blade 5. The body parts have external side faces which are flat around central recesses. When the side face of a body part is in engagement with a flat surface 4, such as a wall, the tip of the blade is a predetermined distance from the plane of the flat surface. When the end face of the body is brought into engagement with a surface transverse to the flat surface, such as an architrave 3, the knife can be drawn down in a stable manner to cut the wallpaper at the predetermined distance in a neat fashion.The two parts of the body are identical and contain crossing inclined grooves to contain the blade so that it projects from a corner of the body.