firstly new guy so please be gentle - don't flame too much !
Recently there have been some new flatted developments/conversions going up in my area. The builder is fitting new European sized euro sashlocks (key outside/thumbturn inside but also letterboxes).The letterboxes may be the recommended distance from the t/turn I've not checked yet. What would you fit to improve the security/get insurance approval. Would you fit a deadlock above or below the sashlock?