The Royal Duchess mark is a distributor/retailer mark found on items produced by various factories. The "Mountain Bell" series is the off-brand version of the Lorenz Hutschenreuther (Selb) #1989 pattern (1960s/1970s). Some Royal Duchess items with faint C.M. Hutschenreuther (Hohenberg) marks are from the Olivia series (1950+).

M090626a
Cover-up transfer with "ROYAL DUCHESS" above a crown above "FINE CHINA" and "BAVARIA - GERMANY".