With a reasonable 13.75" x 4.5" table, the Zyto horizontal milling machine was of a very similar concept to those offered by, amongst others,  the fellow tool and machinery dealers Pools of Nottingham and Bonds of London. The machine's true origins are unknown, and it could have been built in-house, or bought in from one of the many small jobbing engineering companies in the area to the north and east of Derby. perhaps from Portass in Sheffield - or even from  Mr. Freddie Coals in Woodford Avenue, Southend Road (just off London's North Circular Road) - a maker of various lathes including those branded Granville and Corbett's.
Although production dates are not known, as competing machines were advertised into the 1960s a date between then and as early as the 1930s would be a possibility.