A point worth mentioning. Don't just think about security for when your trailer is parked. A few weeks ago I came out of starbucks on the way home from the abattoir to find a couple of pikeys checking out my trailer. They had a van with a towbar sitting a few spaces away and could have been away up the dual carriageway and miles away in no time at all. Big chain, big padlock everywhere I go now. We've had a livestock trailer stolen before and the hassle caused was massive.