Mr Smith is 60 years old and presents with sudden onset chest pain when walking to the supermarket. He was going past the GP surgery when the pain occurred and shouts for help. You are the duty doctor and go out to assess him in the car park. Mr Smith is known to have Hypertension and knee Osteoarthritis. You proceed to examine him and take a history whilst doing so.
Which one of the below clinical features is most likely to correlate with a working diagnosis of aortic dissection?