Back to the bonding route -
Is there removable floor covering?
Nope. It's some kind of extremely hard plastic bonded to the concrete floor. It's all being replaced though, next year sometime.
Could a very small channel be made in the concrete?
Potentially, yes, but I'd have to cut through the current flooring. How deep would it have to be? I worry that kitchen units will eventually be attached to the floor above it and the floor may get drilled into.
When all's said and done though, that wall will mostly be covered with units, apart from about three feet near the cellar door, so I'm starting to think I should just put it on the surface in trunking. :-/ Seems a lot easier.