Taffylou, thanks for the chocks hint. I do recall last time round (we have a 10 yo DD) we chocked under our shelves using rubber door wedges - which worked rather well. However the shelves we have now don't have a rim that touches the floor along the front - meaning the bracketing is really roolly troolly important.

Falguni - oh yes, listening for the sound, well that would've been clever too. However he has a handy person that he works with and is borrowing a stud finder from him. The gadget-ness of the project will no doubt appeal and it will get done a bit quicker.... I hope!!!!