The EF80 internally screened pentode was a workhorse of the VHF TV receiver and was introduced in 1950. It was described by Mullard as: a high slope RF pentode and not a variable μ type. The EF85 was the variable μ counterpart to the EF80.
The EF80 was much used for RF, intermediate frequency, and video amplification.
Thanks to Jonathan Marsh for sending the image of this early EF80.
The thin glass tube envelope is 19 mm diameter and excluding the B9A base pins, is 59 mm tall.
References: Data-sheet & 1040. Type EF80 was first introduced in 1950. See also 1950 adverts.