Tap Advice

[jims-terrano]

Hi all, my mother in law has a dripping tap and has asked me to take care of it.
I have managed to get the tap handles off, one of the spikes unscrews and allows the handle to pull off the splines. Unfortunately this still doesn’t give access to the cartridge. I can only think that some how the chrome body must be a cover that removes to allow access to unscrew the cartridges. It looks like there is a round collar that covers the cartridge but I can’t see a way of removing it.
Any advice welcome.