Now then! We have done a bit of research on this banjo uke and as far as we can tell, it is the same model George Formby used and has a serial number that would place it mid 1940's. 
It was made for export to Honk Kong and still has its original case and vellum with a George Formby signature.Considering its age it is in exceptional condition.Any prospective purchaser is highly recommended to view before buying as this is a rare instrument and needs an expert eye casting over it! 
Made by John E. Dallas and Sons Ltd., this is one of a range of ‘George Formby’ Ukulele Banjos. Each model had a badge pinned to the peghead with the image and printed name of George Formby and also a stamped autograph on the vellum -This particular model is the MODEL D.A special concert model, it has a birds eye maple neck, body and resonator with inlaid edges and a highly polished finish. The fingerboard is ebony and has sixteen drawn wire frets and pearl position dots. It has an eight inch flush rim, an extra heavy bezel with twelve sunk pull down rods tensioned by removing the resonator to gain access to the tensioning nuts. It is fitted with a metal tone ring and tone plate and has an extension tailpiece and sleeve guard. All the metal parts are chromium plated. Usually fitted with a ‘Jos Rodgers’ vellum. Complete with original case.