This is the only V24 that we have seen that has the Marconi paper label on the envelope. The indication is that this was made for sale rather than use within Marconi's own equipment.
The Marconi V24 valve was a development of the 'R' type aimed at improving the high frequency performance. The V24 was designed around 1919 and was used as an RF amplifier with a filament current of 0.7 Amps. The anode voltage would have been in the range 24 to 50 Volts. The V24 itself being an indication of the use of standard 24 Volt supplies of the type used on board ship for lighting.
The grid and anode connections are to side pips on the envelope and the single strand tungsten filament runs from cap to cap, with a spring for tensioning. The construction is co-axial with the helical wire grid surrounding the filament and fitting within the cylindrical anode. In this valve the 'U' shaped glass support holds two stout wire rods that attach to the anode and grid respectively. These electrodes are thus only supported at one end.
The Marconi label.
Taken from the filament tension spring end, the concentric electrodes are clearly visible. The single strand filament is intact.
The other end of the filament.
The thin glass tube envelope is 19 mm in diameter and, tip to tip is 73 mm tall.
References: Data-sheet & 1003. Type V24 was first introduced in 1919.