Dating mullard valves
This site may be of some use: onclick="window.open(this.href);return false; I can only guess you're talking about real Mullards, not the recent New Sensor production with "Mullard" labels.
The good old stuff can be confusing with all of the different labels (and re-labels, and sometimes re-re-labels!! But there should be a date code, and the site above should be able to help you with that.
Sometimes even the best tube dealers get stumped and you’ll see all kinds of incorrect listings on the web.
Often, the printed brand or printed country is incorrect.
Which is part of the reason it can be so hard to figure out today.
There were a few different reasons a given company would re-brand or write the wrong country of origin on a tube.
Another little chart that might help: onclick="window.open(this.href);return false; If you have the Mullards in hand, you can always put them in an amp and fire them up to see if they are Mullards or not.
If you look carefully, they don't look exactly identical.When trying to identify a tube it makes the most sense to first determine where it was made. Depending on where it was made, you there are different clues to look for.