This is Damley’s Patent Rotable Lightning Calculator, Pencil Case, Ruler and Measure.  Calculator is a lithographed tin plate child's Arithmetic teaching aid combined with a pencil case and measures 9.5” in length.   It was patented in September 1920 by P.H. Darnley and B. Richards and manufactured in 1920 as a Times-Table Calculator, a device for learning multiplication and division.  Marked British Patent No. 167699/21 & German Patent No. 397458,  Operation is via two concentric cylinders, the outer rotates about the inner which is held. End caps can be removed to allow pencils, etc, to be stored within the cylinder.  It is operational and shows light paint loss.