Bait Box or Lunch Box ?

Dear Peter,

I have recently come across a rather odd and funny expression. My friend who is from Burnley keeps referring to his lunch box as a 'bait box'. I am a Londoner and I have never heard anyone talk about their lunch as bait. My friend swears by it and insists that it's a Lancastrian expression. I am wondering if you can shed some light on the matter? Is it a common expression in Lancashire? Where does it come from? Many thanks! Alice