The CV2007 is the CV491 with tapes welded to the pins.
The valve is a double triode with separate cathodes. An amplification factor of 17 is quoted. The prototype was the 12AU7.
The original production was as A CV491 and this appears on the glass with a line through it.
The KB/DA identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the DA identifies the maker as Mullard Radio Valve Co., Blackburn.