Abstract: A straight edge cutter guide for use when cutting a web such as wallpaper after it has been hung on a support surface which is normal to or inclined with respect to the horizontal plane comprises a blade, a handle and spirit level indicators. The blade is rigid and has a straight edge extending longitudinally along one edge thereof. The bottom face is flat and has a sufficient area to provide a stable base for the cutter guide. The handle is mounted on said base and has a hand grip portion located above the top face. The hand portion is accessible for use when retaining the base in any required position with its bottom face bearing against a web in use. The level indicators are mounted on the cutter guide so as to be visible when said bottom face is operably located.