This well known site now offers many Jethro Tull music scores and the possibility of listening to them. They are not specially expensive, though not free:

http://search.musicnotes.com/?instrument=Flute&artist=Jethro+Tull&u1=instrument&u2=artist&ca=0&cmpid=eml_smflute

Ta for sharing the link! After a quick browse, I was disappointed to find "Velvet Green" not included. I am pretty good at playing by ear but there is a key change in that piece I find difficult.

Thanks for posting! Just glancing down the list, I saw a couple that I don't remember being in the flute lead-sheets (http://www.sheetmusicplus.com/title/Jethro-Tull-Flute-Solos/7429813) they released. For a collection, that might be more worth your money, but for individual songs, that looks great.

Note: Ian released the first page of the original scores to a couple songs on the Tull website, Velvet Green among them. I don't know how much this will help you (it sure has a lot of modulations in it) but here they are: http://www.j-tull.com/fans/sheetmusic/index.cfm

Egretboy, Ta for the lead. Unfortunately, only part of the first page of the score is posted (and I'm not certain I will be able to follow the notation).

I found another site that does not have Velvet Green but does include a goodly amount of Ian Anderson material: http://search.musicnotes.com/?q=Jethro%20Tull&hl=y&cmpid=AFF_linkshare&arp=2&affsid=LS-Affiliate. Do enjoy!