Thanks for your input. I believe the main photo of the bottle is taken a little from above making the level look a bit lower than it is.
I measured the level and it's 2.5cm from the bottom of the cap. Is this unusually low for an old bottle?
The bottle is definitely old as my father had it for a very long time, exactly how long that is I'm unsure. The only reason the level has been compromised is due to age.
Yes I would be interested in having the bottle's age discovered if possible, as I'm sure it would assist me in selling it.
Please let me know if your require anymore photos.
Your assistance is appreciated.