These doubts about the authorship of BWV 565 were elaborated by Peter Williams in a 1981 article. Hypotheses proposed by Williams in that article included that BWV 565 may have been composed after 1750 and may have been based on an earlier composition for another instrument, supposedly violin. Williams added more stylistic problems to the ones already mentioned by Bullivant, among others the parallel octaves throughout the opening of the toccata, the true subdominant answers in the fugue, and the primitive harmonies throughout the piece, with countersubjects in the fugue frequently moving through thirds and sixths only. All of these characteristics are either unique or extremely rare in organ music of the first half of the 18th century.