"No Fume" conical smokeless ashtray in brown Bakelite, c.1930s

A c.1930s cone-shaped smokeless ashtray in dark brown Bakelite, measuring approximately 10.1cm in height and 9.7cm in diameter at the base, which is marked "No Fume / TRADE MARK / PATENT NO. 253518 / REGD.DESIGN NO. 829977 / MADE IN ENGLAND".  The top has been discoloured and slightly blistered by heat; there is some marking and scratching to the exterior and age wear to the base edge, together with some chipping to the screw thread of the base; the inside is marked through use and would benefit from further cleaning.