I think it's simply quite common that when portraying other nationalities or ethnic groups who are not important except for the plot, they are decribed as stereotypes as opposites to "us", in this case the British.
But if you take the British Prime Ministers, they aren't described very positively, either. Churchill clings to power despite his old age and illness, Eden tries to supplant Churchill by going to the King and makes a monstrous mistake in Suez, Macmillan is cuckolded by his wife and made a fool by trusting Profumo, Heath is totally cold towards miners. Only Wilson has no fundamental flaw or mistake after the Queen learns that he is no spy.
But the difference is that we hardly notice this because every Prime Minister, except Heath, is described as an individual. At least until the Queen says to Macmillan that she has had three Prime Ministers: too old, too sick and too weak.
But even that doesn't negate that Churchill has charisma and past achiecemants during the war, and the shows tells movingly of his refusal to accept his decay due the old age. Plus his demons that he tries to suppress but also decribe by painting the pond.
BTV, the Americans laughed at Eden when he lay unconcious after taking drugs and saw it as a fitting symbol of the decay of the British empire.