Green’s Dictionary of Slang

a concertina.

1914		G.B. Shaw Fanny’s First Play I 175: If you can get Holy Joe to sprint a hundred yards, I’ll stand you that squiffer with the gold keys... What’s a squiffer? [...] a concertina.
1934		‘Ian Hay’ David and Destiny 78: What exactly is a Squiffer [...] Strictly speaking, a concertina. By a process of excusable exaggeration, an organ-bellows, or even the organ itself. By a characteristic confusion of ideas, a person who blows an organ .