The 1C6E is a variant of the 1934 1C6 heptode or Pentagrid converter as it is known in America. Used as a self oscillating mixer for radio receivers designed primarily for local station reception. As was typical with Pentagrid converters the signal grid is taken to the top cap for maximum isolation of the signal from the local oscillator.
The outer grids are circular whilst the inner grids are oval.
From the center out to the left we have the filament, then the oscillator control grid. Next is a broad vertical plate. One either side of the cathode operate as the local oscillator anode. This grid has no wires. Further out are the rest of the wire grids. The fourth grid can be seen to be connected to the top-cap.
The classic envelope is 38 mm in diameter, and excluding the UX6 base pins is 99 mm tall.
References: Datasheet & 1043. Type 1C6E was first introduced in 1936.