Your hunch that the Silver Queen is a kind of Watling/Bell-Fruit missing link appears to be correct OB.
Freddy Bailey describes the convoluted story of how Watling tooling made its way from Bell-Fruit Corp., Reno, Nevada, via France to Northern Ireland and eventually to Bell-Fruit Manufacturing Ltd. in Nottingham: The History and times of Bell-Fruit Manufacturing Co., Ltd.
we're told was made in 1958 using Watling tooling by Sam Norman of Balfour Marine (Engineering) Ltd. (based in Ilford, Essex) under license to Wilkinson & Prock, five years before Bell-Fruit (based in Nottingham) was formed. Balfour became better known as BAL-AMi, making jukeboxes from 1958-63. The BAL-AMi Jukebox website has lots of information about the company and shows a similar red-cased Silver Queen: Behind the BAL-AMi Factory Gate
Operator Bell wrote:I've never seen a mechanical slot made by Bell Fruit.
Derek Horwood explains, in this Coin-op Community article, Ken Wilkinson & Bell Fruit Manufacturing Company
, how the Bell Fruit Model 7-T (TIC TAC TOE 777)
was designed by Lou Bennetti and "then produced in the Nottingham factory under the supervision of Lane Fleischer who was Lou Bennetti’s partner in Reno".
I hope Freddy gets that book published one day.