How do I get at the cold ceramic cartridge on this tap to replace it?
Do I need to take the tap off the sink or can I get at it in position on the sink?
Cheers to anyone with the answer!

Depending on the model number and type of faucet the procedure is different. Most of our faucets would require a 17mm wrench or deep socket to remove the cartridge. You would not need to remove the faucet from the deck or basin to get to the cartridge. If you need further help feel free to contact me at Hansgrohe Technical. 1-800-334-0455. Press 2 for Tech and ask for David Scarborough. I'll be happy to help identify the faucet and get more detailed instructions.