The Restaurant at The Cumberland Hotel
The Cumberland Hotel's restaurant is recommended by writers. Of the 3 professionals that we tracked, 2 acknowledged the restaurant, like Oyster and The Telegraph.
The Cumberland Hotel 
Oyster
The Telegraph
Oyster "Beyond the beach, on-site facilities are rather extensive, including indoor and outdoor pools, a spa, and restaurants that offer poolside dining, afternoon tea, and Sunday "British roasts" in addition to the usual meals"
The Telegraph "It has a student city behind and miles of beach below, and it is home to an easygoing two-AA rosette restaurant"
