Twinings Tea - 300 Years Old This Year
I was making myself a nice cup of Twinings Irish Breakfast when I noticed on the side of the packet that they were founded in 1706 and have been at the same address in The Strand ever since. It also said that they had been “making tea for over 290 years”, so obviously the packaging predated 2006. 
They have a (Flash based) history of Twinings and Tea and, for those who can’t stand or read Flash, there is an HTML history on their US site.
Apparently they had the Govenor of Boston as a customer in 1773, though they claim that a writer of the time (unattributed unfortunately) recorded:
“…it was not Twinings tea the Boston rebels tossed into the sea.”
Obviously they too agreed that they do make a rather nice brew.
At one stage they even had their own bank, though they eventually amalgamated with Lloyds bank in 1892.
