Welcome to the message board adon30.
I guess nobody has answered your question because nobody knows. That is a very generic lump of glass that could have been made almost anywhere, it is so unlike any B&T item that I suspect it has nothing to do with them at all. Maybe it was somewhere your father simply kept odd or spare labels for whatever reason.
A Swedish company Lindshammar made blocks in various colours but no doubt they were not alone.
There is a habit on Murano for using the same basic label for various companies, the idea being that the label gives authenticity - the item was made on Murano and not elsewhere. Different letters or codes on the label would indicate different companies, there is a labelling system of that sort in operation today. The rooster is one of the traditional symbols of Murano.
John