See this thread for information on the company of Stevens & Williamshttp://www.glassmessages.com/index.php/topic,58263.msg330146.html#msg330146
where it is established that:'- whether or not a product was made under a product range that Stevens & Williams had denoted as the range 'Royal Brierley Crystal' is irrelevant for the purposes of correctly identifying their wares from 1846 until 28th May 1985
- all products produced by Stevens and Williams from 1846 up until 28th May 1985 can legitimately be referred to as:
'A Stevens & Williams (insert range name or just insert item name if range name not known)' .'
There is an outstanding question on that thread - '- at what date they decided to call their products 'Royal Brierley Crystal' is still to be determined'
According to this information from source - English Heritage:http://www.britishlistedbuildings.co.uk/en-488295-royal-brierley-crystal-works-
it states within that information that
'The patent for "Royal Brierley Crystal" was taken out in 1926 and subsequently became the company's brand name.'
So we have a date that they took out the patent for the brand name.
However it doesn't give information as to what date that brand name started being used.'HISTORY: During the late 19th century, Stevens and Williams became renowned for the quality of their engraving, in particular intaglio work, on crystal ware. In 1919 the company were awarded a Royal Warrant by King George V, and the works were visited by the Duke and Duchess of York, who later became King George VI and Queen Elizabeth, in June 1925. The patent for "Royal Brierley Crystal" was taken out in 1926 and subsequently became the company's brand name.'
This is irrelevant in many ways because it is about a brand name not a maker, and so doesn't affect the legitimate naming of a product produced by Stevens & Williams during the period from 1846 up until 28th May 1985 being called 'Stevens & Williams'.
However it is interesting (to me at least) because there has been so much speculation about what to call certain 'ranges'.