You see a 60 year old retired headmistress for a blood pressure check and note the presence of clubbing. She tells you she gets frequent chest infections and often has a productive cough. Other than this she is keeping generally well. She had Asthma as a child but has not required an inhaler for several decades. She is a non-smoker and denies any weight loss. You proceed to examine her chest but have a strong working diagnosis based on the history so far.

What is the most likely diagnosis?