'Penguin' ZX Spectrum to PS2 Keyboard interface. Fits on the expansion port and has a through-connector, so it can be used with another interface.

The interface works perfectly when the keyboard is connected directly (standard UK keyboard + Windows keys). I have an issue in that the keyboard is unresponsive when it is connected through my Belkin KVM, which all other systems are connected to.

Having a single remote keyboard for just one system isn't really an option, so I need to do some further digging. No support from the supplier to help try to debug this.