The last time we had Dublin Bay Prawns was after the Dublin Bay Prawn Festival (imagine dreaming up such a thing). Having driven out to Howth and back again, there was not time to make prawn stock. So, I thought the best thing to do was to freeze the shells and heads for later use. In my mind, later can mean any time in the future. That is, unless the Wife decides that there was not enough space in the freezer and my prawn shells have to go.