Two thirds of the way into Joanna Blythman's Bad Food Britain I was feeling a little smug. I try to buy independently when I can – no small feat as I live in a working-class food desert – I cook from scratch almost every day and I rarely eat processed food. My body rebelled anyway. It refused to take anything on board and violently expelled any left overs from both ends. Fabulous. I'm not entirely sure what I'd planned for the first week of the holidays but five days in bed with sickness and diarrhoea hadn't been mooted as an option.