I remember when the pound coin was first minted and I am 55 years old.
In 1915 or so, a single pound (GBP int al) was a banknote ie paper money and was thus until the coin took over in the '80s I think it was. The pound coin is not made of gold.
A gold sov. is something completely different. However "sov" is a nickname or perhaps a euphemism for a pound (GBP).
A sovereign was officially the pound coin from 1817 until 1931, when gold convertibility was abolished. Although it slowly vanished from active circulation from the beginning of WWI.
(On a similar note, in 1919 the silver coins were actual sterling silver with £1 being approximately 113g of sterling silver.)
