I've been told that I have taken a 'belts and braces' approach to my research. I haven't a clue what this means. Old fashioned? Over the top? Does anyone know?

It means that you are being overly cautious. In its original context , it meant that if you wore a belt and a pair of braces then your trousers would never fall down- but you don't need to!
Personally, one of my favourite sayings!
HTH

Thank you STH. Have a star!:-)