Hilton HHonors - Can you tell me about London Hilton & C/I as Diamond?

Staying at this property in award stay. What
can I expect or should I ask for at C/I as
Diamond? Thanks

Go to the diamond desk to check in. Take the terms and conditions to check in with you. Fax a polite note to the manager in advance.
I've stayed there on a paid stay and they took a bit of a nudge to give benefits of status.