Added @BarryIfe's preface

README.md

@@ -3,9 +3,21 @@
 This repository contains the Sibelius source and PDF sheet music of a **typographical facsmile**
 of the Barcelona MS 1964 manuscript containing Domenico Scarlatti sonatas.
 
-## Credits
+## Preface by Sir Barry Ife
 
-The creation of this digital edition was overseen by Sir Barry Ife (@BarryIfe).
+The creation of this digital edition was overseen by Sir Barry Ife (@BarryIfe), who writes:
+
+> I first became interested in Barcelona MS M1964 when I was asked to review Agueda Pedrero-Encabo's edition of three 'unpublished' Scarlatti sonatas for Eighteenth-Century Music. In fact, the title _Tres sonates inèdites per a clavicèmbal_ was something of a misnomer as two of them (the sonatas in E and A, nos 31 and 34 in the MS) had been previously published by María Ester-Sala, though admittedly in less convenient formats.
+>
+> M1964 contains 39 sonatas attributed to Scarlatti, of which 37 are in Kirkpatrick's catalogue. A major point of interest is that this MS formed the basis of the 26 transcriptions that Enrique Granados published in 1904/5. But the MS is clearly an important C18th source for Scarlatti and as one of my doctoral students, Marisa Gupta, was in Barcelona at the time, I asked her to get me a copy.
+>
+> While many Scarlatti sources were clearly made by professional copyists and are clean enough to play from after a few moments of familiarisation, M1964 is anything but. It was clearly compiled from several smaller manuscripts and copied out by an amateur collector. The orthography is messy and the result is often extremely difficult to read or to play from.
+>
+> I therefore decided to make what I call a 'typographical facsimile' which is a concept taken from literary and textual studies. Unlike a photographic facsimile, a typographical facsimile reproduces the features of the original text as closely as possible but in a way that makes it more convenient for the modern reader to read, or in this case, to play from. So the musical text is transcribed exactly as in the MS (one or two precautionary accidentals are added in red) and the stemming, beaming and other orthographical features are also exactly as in the original even when they run counter to modern practice. The result is a text that can be placed on the music desk and played from, and which is a useful crib for anyone wanting to consult the manuscript itself.
+>
+> The text was set in Sibelius in 2016 by a graduate student at the Guildhall School, Chris Lewis, and both the `.sib` and `.pdf` files are available here. A printed copy was deposited with the library in Barcelona in December 2016 and a few other hard copies have been given to professional performers.
+>
+> Any transcription errors or suggestions for amendment should be notified to [email protected] who will be grateful to receive them.
 
 ## Contents
 
@@ -54,7 +66,7 @@ The 31st and 34th sonatas do not appear in the Kirkpatrick catalog. Neither are
 31. _Sonata in E major (which Malcolm Boyd attributes to Scarlatti)_
 32. _K. 23_
 33. _K. 16_
-34. _Sonata in A major (which Malcolm Boyd attributes to Francesco Corselli)_
+34. _Sonata in A major (which Malcolm Boyd attributes to Francesco Corselli, as does Rosario Alvarez in 1989 from Tenerife manuscript source)_
 35. _K. 25_
 36. _K. 27_
 37. _K. 17_