Back in London we turned our attention to more modern intoxicants. We'd been asked to create cocktails for visitors to the Museum of London's pirate exhibition late opening. The MoL's Docklands site has a full-size reconstruction of the dark, winding streets of Victorian Wapping, complete with a wild animal emporium, ale house, sailor's lodgings and a corner that smells of piss. We were taking over the ale house for the night and wanted to make cocktails that explored the gustatory and moral implications of piracy, combining the preferred drugs of historical pirates - booze - with those of modern Somali pirates - khat. Khat is an East African plant that stimulates like amphetamines. It's not illegal in the UK but it is jolly hard to find. With only a day to track it down we tore through Somali shops across the capital taking in Brixton, Peckham, Harlesden and Paddington. Asking for khat we were mainly directed to pet shops but we finally ran it to ground in Finsbury Park. It is airlifted here to be consumed fresh and comes delicately wrapped in banana leaves. It has a punchy flavour, like eating a freshly plucked bay leaf. We turned it into a home-made bitters to finish our gin cocktails. It's not often you have to warn people with heart conditions to stay away from the refreshments.