The Cosmos A45 is a bright emitter receiving triode that was introduced in April 1925 by Metro-Vick Supplies, a subsidiary of the Metropolitan Vickers Electrical Co Ltd. The first production had a metal base skirt and later types had the bakelite skirt as shown in the picture above. The M over V logo can also be seen as can the filament rating of 4.5 Volts at 0.6 Amps. Both versions employed the same 30 mm wide envelope.
The valve was a general purpose type with an amplification factor (μ) of nine. The control grid voltage range was between 0 and -6 Volts.
Looking obliquely at the valve the etched lettering and logo is easier to see. The filament is given as 4.5 Volts and 0.65 A. In practice a bright would be operated with just sufficient power for good reception as under running the filament extended its life. This exhibit was purchased from a picture showing a nickel base shell but in fact it is of the later plastic type. The filament is good and is a single vertical strand. The cosmos brand can be seen on the underside of the base shell.
The electrodes were visible at this inclined angle under the gettering. The helical grid is clearly visible and the single strand filament can also be seen clamped to the lower support.