Very interesting, think that I went that year.
note the Buck & Hickman stand at the start.
If my memory serves me correctly, HMS Magpie was commanded by the Duke, and the model was later placed on display on board HMS Britannia, wonder if it is still there in Leith?
After this visit, the "Duke of Edinburgh" trophy was awarded, but I think it was a few years later.
The visit was reported in ME, and the then editor J N Maskelyn is to be seen showing the Duke the railway & Traction Engine Models.
regards
BB