If a radar service is notified as available in the UKAIP, then it's available to all operators who wish to participate subject to coverage and unit constraints.
But if Oxford want to limit the hours of operation, or even cite; "As directed" then that's up to them, isn't it?
I also thought that the money in the LARS pot does not increase if a new unit takes on the task, that any new LARS unit will take money away from existing units.