During the 20th century it was common for makers of both medium to large backgeared and screwcutting (engine) lathes and plain-turning precision types to offer accessories to convert them into production models. These adaptations varied from a simple bolt-on, hand-operated, bed-mounted turret assembly and a cut-off (forming) slide, to more complete jobs sold only as production versions that could not be turned back into an ordinary centre lathe. Typical examples were those by the English maker Raglan, with a series of machines based on the Little John and "Five-inch", the American Hardinge  TFB-H, HC-CAT, HSL59 types (all based on the DV59 plain-turning model (itself an adaptation of an earlier type) and Schaublin in Switzerland with their highly-adaptable and well-known plain-turning 102.  However, while all the forgoing were modifications of good-quality machines, the Monarch used as its basis an even more costly, first-class, fully-specified toolroom model, the 10EE. As such it would have been enormously expensive and must have had, therefore, a very limited appeal. The situation was made worse by the lathe being a complete conversion, with no screwcutting facility and the ordinary carriage removed and replaced by a powered 6-station turret. As such, with its limited capabilities (and in stiff competition with dedicated production machines) it is very rare, with not even the maker's 10EE sales literature (at least that seen by the writer) making any mention of the model.
If any reader can add more to the story of the 10EE production lathe, the writer would be interested to hear from you..