Gregg Wallace and Cherry Healey are beside themselves with excitement tonight as they learn how chocolate digestives are made.

Gregg has a ringside seat on the production line at Europe’s largest biscuit factory in London, while Cherry is in Manchester to secure the chocolate, which must be processed in just the right way so that it coats the biscuit and melts in your mouth.

Poor Ruth Goodman is sampling a notoriously unpalatable army ration biscuit and learning about its earliest incarnation, when it was considered a cure for everything, from upset stomachs (hence the name, digestive) to typhoid and scarlet fever.