Hi, Eliza.
As I said in the link I gave earlier, the 'swing' or 'bezazz' can be accounted for:

The music is almost identical. The differences being the addition of guitar chords, the addition of an simple melodic accompaniment line (with intro) giving the Calypso beat for each line (dotted crotchet, dotted crotchet, crotchet). Also the final bar gives both notes as crotchets, with a crotchet rest and then the first note of the next verse.