Thanks everyone for the recommendations.
Art of the Fugue, see: Musica Antiqua Köln
There isn't an internet upload of this anywhere but I found an enticing organ rendition by the great Helmut Walcha.
A sample of Musica Antiqua Köln's recording: Contrapunctus 1
Thank you for the Walcha.
The instrumentation alternates between a small chamber (period) string ensemble, sometimes with continuo, and solo harpsichord. Although solo keyboard is probably the intended instrumentation, the performance is timeless.
If you plan to obtain a hard copy of this performance, I recommend this version, if you don't mind used CD's. The performance of A Musical Offering is also exceptional.
Many thanks, I ordered this from amazon and it is an excellent recording. I am now trying to download the Brandenburg concertos
played by Musica Antiqua Köln found here
, as I'm currently only familiar with the Il Giardino Armonico rendition.
I also discovered what looks to be an interesting documentary
about Bach, The Art of Fugue, Helmut Walcha and his pupil George Ritchie who later gives a lecture including practical examples from the work. Once again there is no full upload to be found as yet.