Many thanks to Mike Lavocah for taking the trouble to email and correct me on the story of Troilo and his arrangers. He writes:
'Troilo's main arrangers in those years (1941-1944) were Argentino Galván and the neglected Héctor María Artola. Piazzolla made only ten arrangements back then. He was the main arranger for the band for a time, but much later, in the early 1950s. This information and more besides is in my book on Troilo - I worked hard to research the contribution of the arrangers, as they were such an important part of the Troilo story.'
I relied (as usual) on the information on Todotango which is curiously and sadly incomplete: it says Galván arranged for Troilo in 1940 and in 1945, and makes no mention of his prominent part in that astonishing run of recordings between those years.
I wish I'd seen Mike's book, Troilo, earlier. I got hold of it a couple of days ago. It's a great combination of stories about the people, and insight into the music, how it was made and played. It's researched with access to the Troilo archives in Buenos Aires and includes a discography that mentions the arrangers whenever possible. It's wonderful to have such an excellent and readable account of the people and the music in English, and I can only hope that there will be similar works on other great tango musicians.
It's a great read. 'Troilo... is loved by everybody because he loved everybody. He extended the hand of friendship to everyone, placing himself as the model of humanity. He is everyman, and his music speaks to, and for, everyman.'