This is a 2 part study for patients with solid tumours. The purpose of Part A is to measure the amount of olaparib or its breakdown products in the bloodstream for up to 72 hours after eating 3 different breakfasts (high calorie, regular and none). In Part B Patients can take olaparib capsules daily and study assessments will be recorded for 6 months (minimum). Treatment can continue for as long as the patient is benefitting. Throughout the study patients will be monitored for any side effects.