No sadly it is pre ceramic.
The cheapest new mixer tap with a lever action push up type waste is £65.
The original is a B&Q LOTA item, so not their low rent cheapo item. But it is a little weird in that when you turn the handle a left hand threaded thing inside the spindle winds the other end of the spindle into or out of the spindle until the washer on the end sits on the seat, or moves away from it.
I have spent a lot of time this afternoon searching the internet to try and find a replacement cartridge with no luck.
I have been racking my brain to try and find a way to repair it. The splined part that snapped off is threaded in its centre, the bit it snapped off also has a thread so I will have no trouble centering them together. All I need is a means of interlocking them together. I have discounted soldering as probably being too weak, ditto 2 part epoxy or liquid metal, but I think it might be possible to file profiles in both halves which would then lock them together, held in place by a longer screw, which would also go through the handle. But if anyone has any better ideas I would be very grateful.
(I had thought about drilling very thin holes maybe 1.5mm through both but I would then have to find a way of pinning them together, and the big problem is that there is very little "meat" to do this, more or less a jewellery problem.)
So if anyone has any ideas, I'd be very grateful.