This Cossor rectifier, 43-IU (43IU), is a full wave device with an indirectly heated cathode that is tied to one side of the heater.
With printed lettering on the glass and the classic shouldered envelope shape this looks to be an example of later production than 43IU.
The anode has yet another design in this later example.
Thanks to Mark Mallison for sending the images.
The classic envelope is 45 mm in diameter, and excluding the B4 base pins is 104 mm tall.
References: 1040 & 1043. Type 43IU was first introduced in 1937.