AN-26 UR-CQV about to pass over London on its way from Brum. Odd, they are on ADS0B Exchange and FR24 but not Flight Tracker.
I remember when AN-26s were rare in the UK, I saw one at Gatwick one Christmas, one of five on delivery to Cuba. It had broken down and been left behind. A couple of times I saw Cubana -26s droning eastbound from Shannon, I believe on their way for major overhaul.