The PFL200 combines a screened amplifier pentode and a frame grid video output pentode in the one envelope. It was designed for television use. The mutual conductance of the output pentode at 21 is very high as is required for wide bandwidth amplifiers.
Quality Valve were clearly a reseller rather than a maker.
The valve was used for video output in colour television receivers. Three would be used per receiver, one per gun. The second pentode would be used in the colour difference circuitry. The presence of the internal screen points to the video usage. When used in monochrome receivers the valve was used for video output and the low power pentode as a sync pulse separator.
The B10B base was a late introduction, near the end of the use of valves in consumer products. By putting two pentodes in a single envelope the price would have been lower for set manufacturers in overall assembly costs.
The output section on the left. The amplifier pentode on the right is little larger in front-to-back dimension to a triode.
The power section with slots in the anode wall. The presence of the notched rod indicates a pentode construction and not a beam tetrode.
The amplifier pentode with rectangular folded cathode and copper supports for both control and suppressor grids. The close pitch of the suppressor grid suggests that it could be used in dual control mode.
The thin glass tube envelope is 20 mm in diameter and, excluding the B10B base pins, is 69 mm tall.
References: Data-sheet & 1040. Type PFL200 was first introduced in 1964.