Here we have a very rare instrument! Made by Excelsior as an alternative to the famous 'Shand Morino' this is one of perhaps only around 20-30 ever made.
Judging by the decoration and the bellows straps this is an early model. The spelling of 'Jimmi Shand' was not a mistake but perhaps a way to avoid any endorsement issues!
What we do have is a 4 voice musette British chromatic accordion. Very rare and definitely a collector's item