It is probable that this pen is from 1954-58, so it is a Biro, not a Mabie Todd, although there is a faint “Mabie Todd” imprint at, curiously, the base of the barrel under the cap. It is 13cm long, a lever-filler, with a green marbled plastic barrel and chased (stamped) chrome cap. The gold plated clip is riveted into the crown, and imprinted with “Blackbird”. Its probably gold-plated nib is marked “Blackbird”. It’s a nice writer, producing a wet medium line with a touch of flex.