And so to the lightship Petrel. I didn't think I'd find this, as directions were pretty vague but it rather fell into our laps. Go into Balloo on the A22. At the Saintfield crossroads take the road signposted Whiterock. Go through Killinchy and when yo get to Whiterock, there is a sudden bend to the left. Keep following this road, ignoring a road that leads right across a causeway, and after about 3/4 mile, the lightship is on your right.
Built around 1915, decommissioned in 1968, it has been the headquarters of the Down Cruising Club since 1969. Delighted to find a lightship that has been put to some use.