We can help determine the age of your bottle - but need for you to post images. As for whether it's safe to drink, sure it is - however, throughout the years, the taste may have changed a bit. If you decide to drink it yourself, nose the contents and judge from there. Value? See how old it is first and then you may want to check with companies such as bonhams.com or mctears.com You can also check on ebay to see if there's anything comparable to what you have.
Just some added info.... Victoria Vat was Dewar's main deluxe brand (along with Ne Plus Ultra) from about 1907 onwards. In 1954, the name was changed to Ancestor. You mentioned your bottle has a spring cap - Dewar's started using these type of metal caps during the year 1927. However, during the late 1950s and early 60s, they were replaced by modern screw caps.
Last edited by Jojo; 12-17-2010 at 08:37 PM.