If you tune your uke up to A-D-F#-B, you can play along with Ross Douglas recorded version from the terrific CD Canoe Songs Volume 2. Gives it a nice bright sound. But on BUG night we'll play as is with regular G-C-E-A tuning.
Mike has replaced Ross Douglas's original [Ab7] with [A7] in the PDF version which is fine. But if you want the real Tin Pan Alley sound as Douglas does it, use the [Ab7] chord. Mark has done up a WORD version that uses the [Ab7] chord. An easy way to play [Ab7] when you move to it from the [C] is to play the [C] with your ring finger (3rd finger), then for the [Ab7] keep the 3rd finger on the C (1st string, 3rd fret), put your 1st finger on the 2nd string, 2nd fret, and your 2nd finger on the 3rd string, 3rd fret (in other words move a [G7] chord up one fret) - in other lingo 0323