The ECH35 is a typical triode hexode frequency changer or mixer for broadcast applications.
The CCH35 and ECH35 differ only in heater ratings. The CCH35 is for series heater connection on a 0.2 A chain across the mains. The ECH35 is for parallel heaters only.
Bentley were a reseller of valves and this one is marked as Made in England on the new identification.
The inner coating hides most of the interior. The cylindrical screen is just visible at the top. A Mullard ECH35 with the external metal paint partly removed shows the internal structure.
Looking through the top some of the wire grids can be seen together with the copper supports of the inner grid.
The classic envelope is 38 mm in diameter and, excluding the IO base pins, is 98 mm tall.
References: Data-sheet, 1040 & 1043. Type ECH35 was first introduced in 1940. See also1940 adverts.