but the reference is to the (probably apochryphal) anaonymous letter-writer who would write to the Tmes to complain about some aspect of modern life, and sign themselves "Disgusted of Tunbridge Wells"

"Its image as a bastion of conservative values, has become immortalised in the fictional character of a morally outraged resident: "Disgusted of Tunbridge Wells".

So, Tom is saying that, unlike "Disgusted of Tunbridge Wells", he is perfectly happy and content - "replete" means having enjoyed a splendin meal and feeling "at peace with the world" - and since he lives in Surbiton (itself a byword for cosy suburban living), he is "Replete of Surbiton"