I failed to notice you replied, the colour thing didn't update. My apologies for this late reply.
If your 1911 sovereign does not have a mint mark, then it would be an English one minted over there.
All 1911 sovereigns do not have any numismatic premium, except if its quality is Uncirculated (UNC).
As to the date 1925, that was the last year the English minted
a sovereign coin for circulating money. In 1957 they started minting gold sovereigns again, but not as Â£1 sterling coins but as gold bullion romantically attired in yesterday's garb.
So if the 1925 sovereign has no mint mark it will be one of those last of the British made ones, otherwise it could be S
erth or Pretoria (SA
They were still being made elsewhere however. Australia made sovereigns until 1931 and South Africa stamped out the last circulating one in 1932.
Your 1925 one looks in very good shape. However, generally once a coin is mounted in a holder, it is valued as a piece of jewelery more than a coin. If it has a mintmark you might as well leave it in there.
With the price of gold so high at the moment, you are in a good position.