The 8A8 is from the era of VHF Band III television in the mid 1950's. The valve is a triode pentode, with separate cathodes, designed to function as a mixer and oscillator in the tuner or converter if used with an older Band I television. In the UK Band III television started in 1955.
The article referenced above gives details of the faults and performance of the PCF80 / 8A8.
This imported valve clearly shows the 8A8 to be identical to the PCF80.
The Triode grid grid with copper supports is on the left and is much smaller than the pentode section. Both anodes are carburised.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 50 mm tall.
References: Datasheet & 1040. Type 8A8 was first introduced in 1954.