There is a reference to a Dr John P Dent at 34 (not 24) Addison Road, London W14, in a 1958 US report on drug addiction in Great Britain; and this seems to be the same doctor that Burroughs consulted. (Though the middle initial P is probably wrong, as most sources name Burroughs' doctor as John Yerbury Dent.) The W14 Addison Rd, in affluent Holland Park, seems a very likely address for a prominent doctor. As for the "apomorphine cure" for addiction, this just doesn't seem to have been generally effective. Apomorphine is now mainly used for treating Parkinson's disease and erectile dysfunction. A contemporary said that "Dent without apomorphine would be more therapeutically powerful than apomorphine without Dent", so perhaps Burroughs and other patients were responding more to the doctor than to the medicine.