In 1977 the British range was entirely changed from HO (1:87) to OO gauge (1:76) to stay lined up with the rest of the British market. Also, the British based Irish Lima models were changed to the new scale accordingly. One of the first models was the Mark II coach.
Catalogue number is (30) 5306W. The previous Irish HO model was slightly different to the British counterpart, it had full windows, while the BR coach had ventilated windows. The OO CIE coach had vents like th BR one.
There is a member on this forum, who might tell us the very interresting story about Irish Lima.