SIR Percy Cradock, that strident opponent of Governor Chris Patten's political reforms who is currently in Hongkong, had better beware. We have it on good authority that Government House has secured the temporary services of the fearsome Mrs Wong - yes, Park 'N Shop's very own quality control officer - and asked her to cast a proficient eye over the former Whitehall mandarin, turned Sinologist, to check whether he is past his ''use by'' date. Mrs Wong, who has attained TV cult status because of her dedication to duty, is said to have received her new orders with ominous relish, and is thought to be already on Sir Percy's trail. So, be warned, Sir Percy. The terrifying spectacle of the aforementioned Mrs Wong approaching waving her rubber stamp marked ''Reject'' menacingly aloft is not one for faint hearts. It wouldn't be advisable to hang around town any longer than you have to, my old fruit.