The SP41/U from Cosmos carries the Metrovick logo as well as the Shortpath branding that was used up to 1928. Under the etched type designation on the envelope is the word (half) in parentheses. The design dates from 1927 and the literature states that it is directly heated.
Physically the valve is large for the modest current rating. Unlike our other SP41/U this has the evacuation tube in the base and thus is a later production.
The anode side view. At the base can be seen the heater and cathode tube. Not directly heated.
Some of the etched lettering can be seen including the end of the word HALF at the bottom.
The balloon envelope is 56 mm in diameter, and excluding the B4 base pins is 113 mm tall.
Reference: 1043. Type SP41/U was first introduced in 1927.