Ireland's traffic light system's a little different to the UK.

The sequence is Amber before Red and then straight to green.

Some pedestrian crossings have a different sequence:

Amber before red going to flashing amber for about 10-15 seconds and then green.
You may proceed if there are no pedestrians during the flashing amber phase.

Green fly lights are used like in the UK

Flashing amber fly lights (filter signals) are used quite a lot allowing you to filter out into to traffic. They have the same meaning as a Yeild (Give way) sign.

Red fly lights don't exsist.

If lights are switched off, due to a fault or perhaps during the night (happens in some places) they go into a flashing sequence.

One side will flash amber and the other will flash red.

Flashing amber = Yeild Sign
Flashing red = stop sign.

Generally if police directions are being used, e.g. after a really big match/concert they'll use flashing amber on all police directed junctions.

They've also started installing count downs on busy pedestrian crossings.
i.e. while the "red man" is on a display over the light counts down the number of seconds left before it will go green. The idea being to prevent people from dodging across as they know it's only a few seconds to green.

Dual carriage way signs around Cork anyway seem to display "Red Signal ahead" or "Signals changing" before lights change about 800m ahead of junctions. Quite useful.

As for that temp. light it's quite possible it was hired in Northern Ireland or that the contractor was from N.I. I've seen UK signs used on sites here, particularly near the boarders. It's actually quite illegal.
e.g. "Men at work 500 yards ahead" and the triangle with what looks like a man holding a really heavy umbrella [Linked Image]