The CV4056 is a special quality 6CH6 fitted with flying leads. The B9A based version is the CV4055. However, this exhibit is clearly CV4056 and has B9A base pins.
The design purpose is as a video output valve. The prototypes were the CV2127 and the 6CH6.
The gaps in the side of the anode show the beam plates and the two inner wire grids. Both sets of grid wires are wound to give a flat pass across the face of the cathode.
The Maker's mark on the glass and within the different grid pitches can be seen.
The notch and peen fixing of the grid wires is beautifully demonstrated in this exhibit.
The original Valvo box dated to October 1965. This is a NOS valve.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins, is 60 mm tall.
References: Data-sheet, 1040 & 3002. Type CV4056 was first introduced in 1956. See also1956 adverts.
