The secrets of lost luggage auctions: I bought four bags for 100. What would I find inside?

A yellow suitcase draws me in like a beacon. It is stacked on a dark shelf at the back of Greasby's auction house in Tooting, south London, and looks brand new, with a hard exterior and wheels that Richard Stacey, a Greasby's regular who is dressed in shorts, a plaid shirt and a cream bucket hat, tells me to test. So I test them – and they work. If I was just buying a bag, that is all I would need to know. But this isn't just a bag: the zip is locked and when I lift it, it is heavy.