Fantastic Hand Finished Antique Bottle

We have seen a lot of bottles but this has to be one of the most unique we've ever had. It is a hand-finished bottle manufactured in Great Britain. It has an indented shape all around, probably to facilitate holding which is very unique for its time. We don't know what this may have held - it could have been medicine, alcohol or some food product such as cooking oil - who knows. Great inscription with what looks like a reg number and "In Gt. Britain" - circa 1900 - maybe earlier.