The 2nd below is my favorite. That in the reprinted 'Fitzwilliam Virginal MS' (Dover) has been juggled as far as timing goes, and the rhythm thrown off in some measures and its no good for songs.
Breathnach gives photo of tune in Wm. Ballat MS. To unscramble follow directions just given on the Over the Water to Charlie thread

X:1 T:B051- Callino Casturame (In Summer Time) N:Simpson's BBBM #51 Q:60 L:1/4 M:3/4 K:C c3/2d/2e|e3/2 f/2 e|f2f|e3/2 d/2c|d2d|d3/2 e/2d|^c3/2 d/2c|d2d|e3/2 f/2g|e3/2 d/2c|B3/2 c/2d|B3/2 A/2G|c2c|c3/2 d/2e|d3/2 c/2B|c3|]

X:2 T:B051B- Callino (Wm. Ballat lute bk, c 1580. modern notation) N:from Breathnach's 'Irish Folk Dances and Songs'[?] N:Also in Grove's or New Grove's Dictionary Q:60 L:1/8 M:6/8 K:C E2EE2E|F2FE3|D2DD2D|E3/2D/2ED3|E3/2F/2G G3/2F/2E|D3/2E/2D c3|C2D E3/2D/2E|D3/2C/2Dc3|]