Mullard valve, type TDD2A, gold metallizing partly removed, marked DUMMY, (RMW/Y200 - McVitie Weston number), by Mullard Limited, 1935.
Mullard valve, type TDD2A, gold metallizing partly removed, marked DUMMY, (RMW/Y200 - McVitie Weston number), by Mullard Limited, 1935.