Which British historical defeat stings the most, even centuries later?

We taxed their tea and lost a continent. Arguably the most expensive customer complaint in history.

Harold copped it, William conquered it, and the English language was never the same. Still smarts a millennium on.

80,000 troops surrendered to a smaller Japanese force in what shattered the myth of British imperial invincibility.

Britain marched into Egypt and was promptly marched out by the Americans. The moment we stopped being a superpower.

Fine, swap it for every Euros and World Cup heartbreak from Italia '90 to the present. Football's perpetual coming home, then leaving again.