Mullard valve, type VP4B, gold metallizing marked 2L, marked DUMMY, (RMW/Y201 - McVitie Weston number), by Mullard Limited, c. 1935.
Mullard valve, type VP4B, gold metallizing marked 2L, marked DUMMY, (RMW/Y201 - McVitie Weston number), by Mullard Limited, c. 1935.