O.K., I wanted to get back home and look at my books, although I
probably could have done this close enough off the top of my head.
The Victoria Jubilee Type Sovereign - the one where the Queen wears
the teeny tiny crown on her head - was minted in London each year from
1887 through 1892. The coin was also minted at two mints in
Australia, and the Australians also managed to produce a coin dated
1893.
At this point, the Jubilee Type stopped, period and Amen.
A genuine sovereign coin of this type weighs 7.881 grams.
Queen Victoria died in January 1901 and official British coins with
her visage were coined until the last part of 1901. The next year,
coins of her son Edward VII appeared and he died in May, 1910.
Edwards' coins were made until the end of 1910. Coins of his son,
George V, appeared in 1910 and his bust appeared on British coins
until the end of 1936.
Thus, a genuine sovereign dated 1915 should have an obverse bust of
George V (the grandson of Victoria) and NOT Victoria herself.
After 1932, sovereigns generally ceased to be issued by any Mint in
the British colonial world.
Nevertheless, there was still a great demand for sovereigns and the
price of sovereigns, in paper money, went to a large premium.
Forgers in the Middle East, especially in the area of Beruit, Lebanon,
made fakes to meet the demand. Often these Lebanese products were of
full (proepr) weight and fineness - the premium was so high at the
time that they could do so and still make a decent profit.
However, the Lebanese didn't always pay attention to how they paired
their spurious obverse and reverse dies, and you may well have one of
these.
Or not.
So, the chances that you have a genuine British sovereign are slim and
none (and "Slim" left town); but you could possibly still have
something with a reasonable amount of gold.
If you can send the coin back and have any chance of getting a refund,
that would be the best course of action.
oly
P.S. Victoria's specially made "tiny" crown is presently on regular
display with the Crown Jewels in the "Jewel House" of the Tower of
London.