Oddly enough, Jimmy, there were places we played in, in the North of Ireland during the late 70's/early 80's, where if Amhrán na bFiann was going to be sung at all, we would sometimes be asked to sing it as the very first song.

There was some feeling that the respect the song deserves would not adequately be afforded it, were it to be sung by a drunken audience.

I can see this argument as well, and, in a way, can agree with the thinking.
I must say, though, there is always something 'final' about singing it at the end of the night. There were absolutely no more encores, and as such, the gig had a definate end. But I certainly wouldn't sing it, either in English, or as a 'Polyfilla job' in the middle of a set, somewhere. Only at the start, or at the end of a night.

B.