Gift giving is always a positive thing as opposed to a penalty, which is the opposite meaning of gift. I sincerely do not think that the recipient of a gift in the way of third parties would use the same rationale as it refers to a penalty. With that said, a third party involved in a gift would be deceitful.
Therefore, a tip-giver should be made aware, prior to, this deceit leaving them to judge whether they would like to be involved in the way he/she is offering the tip or gift.
As a tip is used as an added bonus for good service, if the service worker is not even the recipient of the tip, then I think it should be made clear to the patron how the restaurant plans to use this bonus, allowing the customer to choose to tip or not.
I think it important for diners to know if restaurants keep tips in advance. When diners give tips, they do it to appreciate the service rendered by an individual and not the place. So i think it is wrong for restaurants like Harrod to retain those tips, it kills the morale of the workers.
Without a doubt diners should know if the monetary expression of gratitude they are granting is going to the server who made their dining experience pleasurable or to the establishment that employs the server. It would make a huge difference to me if I was contributing to a restaurant that already charged inflated prices for their meals when I thought I was being kind to an underpaid worker.