That's your prerogative but get a set of tubes from the period and look at the stamp. Usually it's two "1"s with one inverted with respect to the other and facing.
I had an early set with 11 bore stamps on it in front of me when I posted, and have seen many more. In my experience, I have to disagree, the first digit is never inverted. They were stamped with a single die.
The left digit is more of a "j" in this case due to wear or pitting.
I suppose anything is possible, but it would take a really strange pit with uniform curves on both sides and perfectly placed to make a "1" into a perfect reversed "J".
Sorry we disagree.
