Hivac valve, type P220, grid pin missing, pinch marked P HBI 28, (RMW/D81 - McVitie Weston number), made by Hivac Limited, aka the High Vacuum Valve Company, London.
Hivac valve, type P220, grid pin missing, pinch marked P HBI 28, (RMW/D81 - McVitie Weston number), made by Hivac Limited, aka the High Vacuum Valve Company, London.