Here's an interesting pic of John and Cliff with The Shads in the background dated November 3rd 1963 which I'd not seen before. It shows Hank playing a Marvin - but without the top 'horn'; is this a prototype? I'm not an expert on the chronology of the Burns Marvin etc during this period but guess this might be of interest to some!
https://www.mediastorehouse.co.uk/memor ... 23509.html