The CV2000 is an HF pentode fitted with flying leads to the B7G base pins. The valve itself is a CV4002 also with flying leads. The B7G version of the CV4002 is the CV4014 the special quality version of the CV138 and that is the EF91.
Neil Bousfield (ZR2DR) has written to suggest that the CV2000 was probably used in Marconi Marine equipment in the 1950s. His information is based on having been given some new CV2000's that were originally owned by a Marconi Radar service technician.
The paxolin base with ribbon leads welded to the valve pins.
Here the welds holding the ribbon to the pins can be clearly seen.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G/F base pins is 48 mm tall.