Yard theatre, LondonA Ghanaian tour guide struggles to maintain his composure in the face of historical ignorance and requests for selfies, in Rhianna Ilube's poignant critique of colonialism and tourism 'Welcome to my first tour of the day," says Samuel to the audience. We're in the courtyard of a former slave castle in Ghana's Cape Coast which housed more than three million Ghanaians between the late 17th and 19th …