At the beginning of 2000, The AA, RAC and English Tourism Council agreed on a standardised rating scheme to which all hotels could adhere. The diamond scheme is for hostelries offering lesser services, such as B&B�s, etc.
Any hotel that has earned such a rating is provided with the collateral materials to advertise and promote their grading.
Clearly, this site does not show who has bestowed this rating upon them. Before I�d jump to conclusions, it might be more appropriate to phone them and ask, specifically, from whom did they receive this rating, and when.
As it stands, I do not believe this hotel is being clear with their description and as such, may fall under the Trade Descriptions Act. However, they�ve shown a quote from the Evening Standard.
Hotels can have their ratings adjusted in either direction for numerous reasons. If it�s done downwardly, it will not have been without an initial warning and then a follow-up inspection.
In other countries (this is not a policy here yet) ratings can be suspended when there is a change in ownership or management. This is a two-way street. It allows the new owner/manager the time to acclimate themselves and it provides a gentle message to the public that there is a transition in place. (good or bad).
I hope this offers a bit of light on the subject.
I wish you well
Fr Bill