The dual pickup "Bassmaster Bass" was one of the earlier bass guitar models produced by Vox. The styling of these early Vox entry level basses was influenced by popular Fender guitar models from the 1960s. It was produced in the UK from 1961 through 1965.
Dick Denney, the lead engineer at Vox, indicated on page 21 of his 1992 book "The Vox Story," that the first Vox guitars were produced under subcontract by Stuart Darkins & Co., a furniture maker in Shoeburyness England. After 1963, JMI severed broke ties with Stuart Darkins and shifted neck production to G-Plan of Hemel Hempstead, another UK based furniture maker. The guitars were then assembled at the JMI facility in the UK.
Earlier Bassmaster basses had laminated plywood bodies while later production used solid mahogany. Production dates were stamped inside the neck pocket.
The compensating bridge used on the Bassmaster is similar in design to those used on Fender basses. A single volume and a single tone control adjusted the dual single coil pickups, but oddly, no pickup selector switch was included. While many Bassmaster basses used a standard 1/4" jack for the cable connection to the amp, some used a factory installed screw-on coaxial antenna style jack.
The sycamore neck used on the Bassmaster had a 30" scale and a rosewood fret board. The neck was quite narrow, only 1 5/16" wide at the nut. It did not have an adjustable truss rod. Rather, it had two non-adjustable steel rods embedded in the neck.
The Bassmaster Bass appears in the 1965 US Vox product catalog, seen below. A reprint of this catalog is available from North Coast Music, just click on the catalog image.

This catalog described the Bassmaster Bass as "A very fine bass guitar with body in selected lightweight hardwood. Fitted with two exclusive Vox bass pickups, separate tone and volume controls, and compensating bridge unit. Polished sycamore neck reinforced with two embedded steel rods, with rounded rosewood fingerboard. Choice of red, white or sunburst high gloss polyester finish."