Irish Lights Flags

In 1863 the Port of Dublin Corporation, which was not only the General Lighthouse Authority in Ireland, but also the Corporation for preserving and improving the Port of Dublin, was granted permission to use the Blue Ensign defaced with a badge in the fly. This consisted of a lighthouse on a circular blue background surrounded by a scroll bearing the words "Irish Lights Department". The General Lighthouse Authority became a separate body in accordance with the Dublin Port Act of 1867, and was designated the Commissioners of Irish Lights. At the same time, the design of the badge on the Blue Ensign was changed.

The flag of the Commissioners is white, three by two, charged with the red cross of St. George; each quarter comprises a seascape - first and fourth showing a lighthouse on a rock, second and third a lightship, all proper. There seems to be no record of the date of the adoption of this flag. Similar charges, only placed within a circle, are displayed on the blue triangular field bearing the St. George's Cross, of the "Pennant". This is flown at the main masthead, but is replaced with the Commissioners' flag whenever they are embarked. The Commissioners' flag is also flown at all lighthouse stations in the Republic of Ireland; however, those in Northern Ireland fly the Blue Ensign defaced, as described above."

https://www.crwflags.com/fotw/flags/ie~comil.html