Implying extra precautions were taken even though they might seem unnecessary. Although the alarm was set, he followed a belt and braces method by also having a guard dog.
Pro Tip 2/3
British Origin
It's a British expression, so be aware it may not be understood globally. Our UK team prefers a belt and braces policy to avoid any risks.
Pro Tip 3/3
Primarily Formal
Better suited for formal or business contexts where precision is valued. The engineer recommended a belt and braces check of the system before launch.