The B319 from M-OV, badged as a GEC valve, was designed for the introduction of Band III television. In the UK this service commenced in 1955.
The B319 was specifically designed for cascode operation as an RF amplifier up to 250 MHz. The cascode configuration was for triode one to be operated as a grounded cathode stage directly coupled to triode two. Triode two was connected as a grounded grid stage.
The other lettering showing the country of origin and that the maker is a member of the BVA.
One triode is on the left, the other on the right with extensive central screening, especially around the left hand unit.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins has a length of 49 mm.
References: Data-sheet & 1040 Type B319 was first introduced in 1954.