Brilhart "Made in England" mouthpieces
The Brilhart "Made in England" mouthpieces were made while Brilhart was in Carlsbad (1954 - 1966) . They were manufactured by ROC and can be identified by the "Made in England stamp below the serial number. Most, but not all, were made with a brass or chrome ring around the neck. According to information from Barry who worked at ROC at that time they were only partly made in England..........
As can be seen on the two pictures below, the UK-made mouthpieces (these are tenor pieces) were larger than their American brethren. The reason for that is so far unknown to me.
The Personalines had a black bite plate, and very few black models were made were made. For all the models, the bite plate was seemingly glued with a not so good glue, so they often fall off. besides that, the quality of the pieces made in England is high. Only Tonalin, Ebolin, and Personalines, and apart from few clarinet pieces, only tenor and alto were made.

 
The following is a clip from http://doctorsax.biz/Britone_Tenor_Mpc.htm

Received an e-mail July 16, 2010 providing the following information:
Hi, just a little information for you regarding the ROC Britone mouthpieces.
The name ROC came about when the two company founders, Norman Taylor (my father) and Harry Chance, were sitting in their office trying to think of a short name for their range of new mouthpieces when a large van passed the window.
On the side of this van was the company logo "Rubery Owen Company" hence the name ROC.
It wasn't long before they remembered that Roc was the name of a mythical bird...hence the logo was born. Nothing to do with Rudall O Carte or indeed Republic of China.
ROC manufactured the mouthpieces from scratch, I should know as I used to be a part of the production team, we also made mouthpiece for at least 6 other companies which were marketed under thier own brand names.
Hope that this info is of interest to you.
Regards,
"Name kept confidential"

In a later e-mail this same informant says:
ROC Instrument Co. stopped the manufacture of mouthpieces many years ago and moved into the manufacturing of office furniture.
Subsequently the company name changed to ROC Office Furniture. ROC was eventually sold in 2006.
P.S. Yes we did make Brillhart mouthpieces amongst others. In fact I have two on my desk, a Personaline Tenor and a Tonalin Alto.