`` actually , i 'm frightfully busy , '' replied a posh voice , `` i 'm in a business meeting , ca n't see you just now , '' `` look , we 've only come to london for a couple of hours , we have to go back to scotland tonight , '' i persisted , although we were really staying for several days with my pal , jim , `` oh , very well , come in , '' the voice conceded petulantly , i told him i wanted to buy some black dope , `` black is just for beginners , '' he informed me with a superior air .