Why does great britain have a large debt? and who should pay that debt?

Great Britain had a large debt because of the French and Indian War, according to the British, the American colonies were supposed to pay that debt through taxes, those taxes later led to the revolution.

WW II drained British financial, industrial, and human resources.  Infrastructure had been neglected for three years, education, health, and government services were understaffed, a huge demographic of young males was decimated, and Britain STILL had responsibilities to many countries in the crumbling Commonwealth.  When the USA actively entered the War in January 1942, that huge injection of equipment, men, ad military resources saved Britain from economic collapse.  But even now, 72 years after the end of the War, Britain is still paying for it.