We believe that the L71 was from GEC/M-OV and was probably the prototype for the E1148 or E1171. The final version was the CV6 and was used in the transmitter of early IFF (Identification Friend or Foe) systems. The anode and control grid are both taken to top caps.
The single triode is mounted quite a distance from the base pins and so taking connections to the top caps reduces inductance and raises the maximum usable frequency.
Face view of the blackened anode. Note the tape connecting the grid to the top cap.
A closer view.
The wide glass tube envelope is 28 mm in diameter and, excluding the IO base pins, is 76 mm tall.
