Foxes and the bin bags

Text 1: Flat 4B, by Wendell Pryce

An original short story extract.

On Tuesday morning the pavement outside our flats was covered in rubbish: chicken bones, eggshells, teabags, a burst ketchup bottle bleeding into the gutter. The foxes had been at the bags again. Mr Grainger from the ground floor was already out there in his slippers, holding up a pizza box with the tips of his fingers. ‘This,’ he said, as I came down the steps, ‘has your name on it.’ He was right. Mum always wrote our flat number on the delivery boxes so the driver would not get lost, and there it was in black marker, 4B, above a smear of tomato sauce. I tried to explain that the foxes did not care whose bag it was. He was not listening. He handed me the box, and a bin bag, and went back inside to fetch the broom.

Explain how Mr Grainger knows that some of the rubbish came from the narrator’s flat.