I, too, am rather proud to be British although it feels a little awkward to explain why satisfactorily.
Having said that, I accept that people both indigenous to these islands, and otherwise, have the right to voice criticisms of these 'sceptered isles'; it's called 'having an opinion' and much as I may disagree or find it difficult to comprehend quite why they feel that way, it is an essential part of being British to let them have their say.
TGT's chest-beating and sabre-rattling is not the British way of expressing dissatisfaction with anything.....that tends to be tutting, casting eyes skywards and writing pithy letters to Points of View.