Margaret Thatcher did much more good than harm. She is the second most important British Prime Minister of the Twentieth Century.
After taking office in 1979 she stopped what had seemed to be an irreversible decline of feather bedding, high inflation and low morale.
She was helped in her efforts by a group of Argentine Generals who were good at torture and making people they didn't like disappear, but no good fighting a war they started off their own coast.
She create home owners from people that had lived in public housing and made London a world financial centre when it had been in decline.
Thatcher got South Africa badly wrong, but luckily wiser counsel prevailed on that issue. On her overall record Margaret Thatcher did much more good than harm.