Found this on the YT and he has a few videos about the Shand 3 row button accordion.

It seems that he had his accordion specially made by Hohner so that he could play all sorts of music. The left side is a standard stradella base setting but the right side with the three rows are diatonic tuned from outside in – B, C, C# This is something of the tunings that I was looking for in the two row Erica. So, on the outside row on the third button down you press the button and push and you get B. Pull on the same button and you get C#. But C# is also what you get on the third button down on the inside row when you push. This is one of the “change” keys. Also, F natural is a pull button on the C row but a push button on the C# row, another change key. There are many change keys, depending on what you are playing.

Brandon McPhee explains the “Button Accordion” B/C/C# Hohner Shand Morino (Scotland)

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Try it, you may like it.

Den.

This is the piece I remember Jimmy Shand playing.

Jimmy Shand - Bluebell Polka

Den,

Here is Brandon McPhee playing his button accordion.

BRANDON McPHEE - “REEL PLAYING' Scottish Music

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He certainly makes it look as though this instrument is easy to play!

Ron

Here's another one of him playing Scottish music.

BRANDON McPHEE - THE BLUEBIRD - Scottish Music

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Hugh

Hello Ron, His and Jimmy Shand accordions are "Special" as the rows are tuned a semi tone apart. Most of the diatonic accordions are tuned to Irish or Scottish music. Commonly G, C, F or Bb Eb Ab which precludes many melodies. Example, G,C,F, has only 2 accidentals. F# in the G row and Bb in the F row. My Hohner is unique that it is tuned B and C and has a 12 button stradella bass. Consequently I should be able to play any song. Basically, you break up the music into short patterns and learn the button location for each. It would be the same on a piano keyboard. Thanks for your comments, much appreciated.
Kind regards, Den.

Thanks for the explanation Den, but the Button Box as it is known in Scotland, will always remain a mystery to me.
Brandon is a fine player of this instrument. He smiles while Jimmie Shand never did.

Ron