Many years ago there was an exercise occurring around the north of Scotland with lots of NATO navies taking part. Sumburgh was landing on 27 and weather was less than optimal visibility wise. All of a sudden a primary target appeared on a 5 mile final moving very slowly and then speeding off to the north followed by several more. The landing ATP was given traffic to which he reported in sight and happy to continue visually. Asked what it was and the reply was "An aircraft carrier launching Harriers!". Turned out it was a Spanish carrier hiding by the Shetland mainland and sneaking aircraft off without being seen. As this was in The Sumburgh CTZ a phone call was made to the man at the ministry and the ship moved off.