Open All Hours S3/E2 • The Ginger Men

Why is Arkwright forcing his ginger cake upon Nurse Gladys? Could it be he has overstocked? When Arkwright finds himself with a surplus of Jamaican Ginger cakes he tries various marketing ploys in order to sell them off, but hits the jackpot when he claims that the cakes contain drugs, which has the customers fighting to get at them. If it really is an old Jamaican aphrodisiac, why is Granville acting like he's overdosed?