This is, of course, much too late but just in case anyone else is using this for research: when we performed this play we roughly fit the lyrics of "Will you come to Abyssinia" to the traditional song "She'll be Comin' Round the Mountain". We assumed it was a rough parody of a traditional Irish song or something rather than an actual song. The tune worked rather well because of its raucous nature, and I think it would be homegrown because of course Mussolini had just invaded Abyssinia at the time this play is set and DeValera and the IRA had just fallen out of the news.

"Dancing in the Dark" must be the John Barker version because of the time the play is set. Type that into Google and you should be able to listen/download. Same with the Henry Hall waltz "It's Time to Say Goodnight". I think Henry Hall also covered "The Isle of Capri" and "Oh Play to Me Gypsy", both of which also feature in the play.

Handy to anyone?