Rosy’s mummy hands Franny a clear plastic bag full of reject biscuits, then Rosy holds her cheek out for Franny’s wet kiss. Rosy wipes the slime from her face and Franny cackles, then shows them both into the lounge.There on Franny’s coffee table is a biscuit tin with a Christmas picture on the lid. Proper shop-bought biscuits, not factory rejects.“Please, may I have a biscuit?” Rosy says.“Oh, there are no biscuits in that my darling,” Franny says, and pulls the tin from Rosy’s prying fingers. Franny holds open the bag of crumb-speckled chocolate digestives. “Help yourself, my wee hen.”Rosy settles for a reject.Franny puts the Christmas tin up high, way up high, way out of reach.

I owe my first inkling of the problem of infinity to a large biscuit tin that was a source of vertiginous mystery during my childhood.

At the end of the school day, we walked the long, cold way home feeling happy and hungry. There we found a warm fire, country ham with gravy and hot biscuits, and a mother to hug us! If snow blew under the doors that night, what did it matter? Christmas time was just around the corner.

I am Nom-O-Tron,' said the machine, in a big, boomy voice, so loud that Astra was afraid her mum and dad or some other grown-ups would hear and come to see who was sneaking a bedtime snack. 'Shhh!' she said. 'Have you got any biscuits?