Mullard made the Wecovalve under licence from Western Electric. The peanut based version was introduced in 1923 as a general purpose dull emitter valve.
The Western Electric 'Weco' came in three sub-types, green spot, orange spot and the red spot version.
A visual inspection reveals a glass top support for the fixing rods. The filament is a single vertical wire down the centre of the tubular anode cavity. The grid is wound as a helix in a wire much thicker than the filament.
The valve came in a cardboard box and the glass was protected by a thick cardboard tube.
The etched lettering is on three lines. The first says Mullard, the second Wecovalve and the last reads protected by patents. The supports are secured into glass beads to make a rigid structure.
The rod at the lower part of the image is the top filament support. The circular loop is the tension spring. The valve is hard pumped and not gettered.
The thin glass tube envelope is 14 mm in diameter and, excluding the base pins, is 63 mm tall.
Reference: 1003. Type Wecovalve was first introduced in 1923.