Bernardo Pasquini (1637-1710)
This theme and variation is from a very old and well known Portuguese-Spanish theme. The score is from a 1954 Schott edition, "SILVA IBERICA de Musica para tecla de los siglos XVI, XVII, y XVIII".
I do not find any other uploads using this sample set, other than a pre-release one, so (Thank you, Augustine) I will give it a try for my first upload. This Partita has been uploaded a number of times with different organs.