Mr Matthews is 80 years old and is worried about his swallowing as for the last few weeks he is struggling with meal times. The first bite of each meal seems to be fine however, and he has a good appetite. On further questioning he is also suffering from regurgitation and a chronic cough over the same timeframe. He lives alone, is a non-smoker and has no other medical history other than Hypertension. He thinks he may have lost a bit of weight but denies any abdominal pain, nausea or vomiting.
What is the most likely diagnosis?