First, your debt citation is ludicrous. Britain was in an all-consuming war which killed a whole generation, destroyed shipping and trade, and sidelined normal industry. The US similarly had its highest debt in WW II, the domestic economy went on a war footing, and rationing was imposed; but our country wasn't bombed to pieces.

Second, Reagan benefitted from the monetary actions of fed chairman Paul Volcker, who ended the stagflation that kicked Jimmy Carter out of office (not Ronnie's technicolor charm), along with the end of the Carter oil embargo that led to a hoarding panic. Reagan was an ignorant man who knew nothing about economics. His adviser David Stockman objected to Reagan's large spending increases while lowering taxes, which resulted in a ballooning national debt, and recently Stockman has declared supply-side to be phony. Business activity increased but working wages grew at a lower rate than inflation.

Reagan cut taxes and increased spending. That didn't work for Bush.