Kitchen under cabinet light switch.

Dr_888

Thank you all. I will go through the estate agent to ask the previous owners.
kind regards,

boom

Zooming on the picture, it's Zigbee controlled unit.  So you're not necessarily looking for a traditional wired switch, you're looking for a remote control.  

So assuming it has power, and you can't find the remote, you may need to re-pair it with a new remote or a new Zigbee hub.

This is your unit by the look of it, you can click on 'downloads' for instructions:  https://www.tlwglobal.com/product/smart-driver-12v-led-smart-driver-15w-with-6-port-micro-plug-connector/