Cazza — Yes, frequently. It's only within the last decade or so that John Lewis's buyers have favoured marked glass; previously if you wanted to sell to them it had to be unmarked. ... and M&S has never had a policy of revealing its manufacturers. Just two examples. Your most valuable and important trade buyers always received the best service, however irrational their requirements, leaving the leftovers for the small occasional buyers.
Sometimes normally marked glass would escape marking. I have a boxed Stuart/Stonier set in stock that you would expect to carry the Stuart/Stonier "=S=" mark on all six glasses. This is decorated in the Cunard White Star wavy line pattern, so was probably a competition prize awarded to a passenger on board either RMS Queen Elizabeth or RMS Queen Mary. Yet it is unmarked. The most likely explanation is a last minute rushed order.
There were no rules other than survival — maximising turnover and profit, both long- and short-term. The more you appreciate the workings of industry and commerce — the more sense you can make of the glass that you are collecting. It's not like collecting postage stamps!
Bernard C.
