I wouldn't class bullionvault the same as holding the physical metal.
Don't see any private sellers with 20% lower than bullion dealer prices either, prices are usually roughly the same as vat added.
If you check my posts you will see recently I bought some bullion with price below spot from individual seller. bulion vault is the same as owning physical bullion. don't see the point saying it's not. you can withdraw bullion from them if you want. maybe try them and then comment.
I have few gold and silver contracts with them and cannot complaint.