Of the three in the middle photograph, I'd have to see close-ups of the charger, of the Left one, (hanging game)to know whether it was antique or not.
I have one the same, but it was made in the 1970's. A close look at how the charger is marked will tell us.
The original moulds were often used, so we see many Dixon flasks, and made by Dixon, but much later than the first batch.
If top is attached with iron or steel screws, this is a good indication of age, as it the horizontal mark in the dram measurements. Not diagonal.
As in all things we can not say always or never, without getting into trouble.
V nice flasks!