Probably the Bell Geospace DC3 with Turboprop`s.
There was an aerial survey aircraft operating around Drogeda last month I believe;it got a mention on the traffic news in case people thought it was in difficulty,and would cause a distraction.
Would this be the NOTAM ?
11) H0267/12: Exercises will take place
Q) EGPX/QWELW/IV/BO/W/000/025/5515N00633W025
LOW LEVEL AERIAL SURVEY BY TURBOPROP ACFT WITHIN AREA BOUNDED BY 5530N 00706W - 5530N 00600W - 5500N 00600W - 5500N 00706W - 5530N 00706W (NORTHERN IRELAND). ACFT WILL OPR BTN 275FT AND 1000FT AGL/AMSL. OPS CTC, TEL 01224 227722 / 227726.
12-02-0099/AS 5.
LOWER: Surface
UPPER: 2,500 Feet AMSL
FROM: 10 Feb 2012 00:00 GMT
TO: 10 Mar 2012 23:59 GMT
SCHEDULE: Daylight hours