PMB,

In case you don't understand TheSnails post above two of the three songs you mention as Irish above were written by Ewan McColl an Englishman of Scottish descent. I might be wrong but I don't know of a song called the Shores of Erin - McColl's song is called "The Shoals of Herring"

Shaneo,

It depends on lots of things - the song, the singer, the session the musicians etc. I know many musicians who love singing and are delighted when someone sings in a session. I know others who hate singing and are likely to pack up as soon as a song starts. Most are between these extremes. It can also depend on the quality of the singing, the style of song chosen and how frequently the singer sings during the session. Or it can simply be a matter that the musician is tired. I often yawn involuntarily during a session, particularly if its late at night. No insult is intended.

Having said that I've often seen singers behave really rudely while tunes are being played at sessions - talking loudly, shouting to their friends at the other side of the room. There are some singers (by no means all) who think that if there are no words to a tune its not worth any respect or being listened to. Some of these are the first to demand absolute silence for singers.

Usually a bit of give and take can sort these things out. If you would like the musicians to back you when you sing, let them know that. Many people still bear the scars (phyhsical and emotional) of daring to try to back a singer who wanted to sing unaccompanied.

If the musicians choose not to that is their choice. As others have said they may be doing you a favour.