The type of closure being used here is a spring cap and these types of caps replaced the cork in 1927. Take a look the bottom right hand corner of the front label and let me know if you see a date - for example, '5/22' would mean May 1922. If you don't see anything, then look on the reverse side of the label (yes, through the spirit). You'll be looking for a reference such as '43-66' - this example means the whisky was bottled in 1943. Let me know what you find out.