Beautifully played here and (cough, cough) there's a gif showing a transcription of how he plays it. I say "cough, cough" because even though lots of people think that Inisheer is a traditional air, it was actually composed in the 1970's by an Irish accordionist, Thomas Walsh. I'm not sure how OK it is to publish the sheet music on the internet, although at the session https://thesession.org/tunes/211
I found this along with lots of abc versions, including ones that will get you a result equivalent to the way it's played at Mick's Virtual Whistle:Regarding the copyright to Inisheer. Thomas Walsh has copyrighted the tune, and he would like anyone who is recording the tune professionally to make arrangements for the use through the publishing company that represents him, www.crashedmusic.com. I am in the process of arranging use of the tune for a CD for the group I am in, and they seem to be good folks to work with. So if you plan to record this tune, give the author his due and pay for use of the rights.
The post at the session said Mr. Walsh is happy to have people playing the tune in public without paying royalties if not recording professionally.
The gif shows the key of D, but there are actually no C#'s in the tune. For CODA, I recommend transposing down a full step/major second - you end up in the key of C. I started by learning it on CODA in the key of D and I just couldn't manage the chamber switches to get the sound I wanted. Even though there are chamber switches in the key of C, they occur at more convenient times. (Of course, now I have to unlearn the key of D fingering).
Also...if you can reliably play a low Bb and low C on an MO, you can transpose down again so that the key is Bb-major and lowest note a Bb - sounds pretty good on my warmstone G.