Issue: Kitchen Sink Mixer Tap Leak...
Inside, I found the mechanism which controls the flow of water is called the Ceramic Disk Tap Gland / Valve
sometimes called online as compression valve/tap glands/cartridge
Wished I'd checked this video before I started
tools I used
how to measure for your replacement
bought mine from Screwfix
unfortunately, the valve snapped leaving half stuck in, flush out the middle as per
then with access to the middle, used chunky pliers jammmed in to unscrew the broken cartridge out
further post mortem reading