The AC2/HL is an indirectly heated triode for mains broadcast receivers.
The identification lettering is etched into the dome of the envelope, as is the BVA logo.
The low power of the design can be deduced from the bright anode and the absence of grid cooling fins. The anode is formed into two U sections placed symmetrically either side of the cathode/grid assembly. The grid is wound under tension and can be seen to lie flat across the cathode and parallel to the anode plates.
When slightly tilted the construction of the anode is revealed. The grid construction is also more clearly seen.
The balloon envelope is 45 mm in diameter, and excluding the B5 base pins is 93 mm tall.
References: Datasheet, 1043, 3002 & 1040. Type AC2/HL was first introduced in 1931.