The CV416 is the commercial 6F17 beam tetrode produced to the UK Government specification based on the VX6055. The design purpose is for RF and pulse voltage amplification and was used in television receivers but RADAR is another possible application as would be test equipment.
The anode is blackened and oval in shape, it is held by flanges passing into the top and bottom mica sheets.
The anode seen end on.
The valve came with two labels. This one shows that it was accepted into stores in August 1964.
This looks like the stores label.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins, is 43 mm tall.
References: Datasheet & 1040. Type CV416 was first introduced in 1948.