Apparently this piece isn't by Albinoni and was in fact composed in the 20thC!! I looked up Albinoni's Adagio on Wikipedia and found that:
Adagio in G minor for strings and organ is a piece composed by Remo Giazotto(1910-1998) while supposedly based on a fragment from a Sonata in G minor by Tomaso Giovanni Albinoni which was found amongst the ruins of the old Saxon State Library, Dresden, after it was firebombed by the Allies during World War II. The Adagio was first published in 1958.
Blimey, I didn't know that.