The RC is from the Cossor Point One series. This series of dull emitter valves took just 100 mA of filament current and each of the variants had their own colour band. The later catalogue Type designation of this valve is 410RC but this is not to be found on the valve itself.
Cossor describe the valve on the label that runs around the base of the envelope as: specially designed for resistance capacity coupling.
The 'top-hat' anode is 5 mm from to back.
The basic operating conditions are printed on the blue paper band.
The construction of the anode supports, grid winding and filament supports.
The balloon envelope is 45 mm in diameter and, excluding the B4 base pins, is 100 mm tall.
References: 1043. Type Point One - RC was first introduced in 1927.