Must be a Pretty Rare Item.
Yes, Mullard disappeared many years ago, like many other British companies.
The Vinkor series of inductors were used in many items of electronic/radio equipment.
In the top row on the left , there are two different sizes of the Mullard Vinkor in their metal screening/mounting assembly. At the right is an unscreened core, not sure who made it but it was sold by RS Components, this one also has an adjustable core.
In the bottom row, a Vinkor unit split into its parts.
Left to right, the metal body/screen, the bobbin lower half of core and terminal panel, upper half of the core, body end and mounting boss, adjusting core, ferrite sleeve on a plastic core.
The plastic core of the adjuster is screwed onto a threaded spigot which can just be seen in the bottom of the base/terminal panel.
JimB