My standard model spiel:
The M-1W is a variant of the M-1, Kay's flagship model from the beginning of bass and cello production in 1937 through the company's liquidation in '69. Characterized by its violin corners and rosewood fingerboard and appointments, the M-1 was the secondmost-popular model after the C-1. We have no indication of the specific purpose of the M-1W variant, which differs from the M-1 only in details of badging and more frequent use of ebonized rosewood for fingerboards, indicating lower-quality wood so likely a lower price. It appears from 1937 as late as '51, but nearly all were built in two brief windows in '39-40 and '49-50, hinting that it may be designed to fulfill a specific contractual obligation to a reseller, possibly a startup investor. I estimate total M-1W production in the 1,900-2,000 range.
I've frequently seen speculation (including a few very firm convictions) on what the W might stand for, but zero evidence. Research continues.
