I am looking for a pencil thin conifer that will not exceed 2.60 in height. I am considering Chamaecyparus “elwoodii” or “stardust”. Perhaps an Italian cypruss, but would it cope with the cold.
Most kinds of conifer, including those you miention, will in time exceed 2.6 metres, and neither of the two mentioned are pencil-thin. Italian cypress copes quite well with cold, but not so well with Irish wind.
A juniper, such as Juniperus ‘Sentinel’ or ‘Blue Arrow’, would be the best bet.