Labour MP David Winnick drew sharp criticism from members of the Conservative benches after accusing Thatcher of treating millions with "brutal contempt."
In a special sitting of the House of Commons to pay tribute to the Baroness who died in the Ritz on Monday, he said it would be hypocritical not to point out the "human cost" of her policies and the immense pain and suffering they caused.
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Two-year-old Casper Platt-May and his six-year-old brother Corey died in the crash in Coventry on Thursday.
It means the petition, calling for a diverse panel to be appointed to the inquiry, has enough signatures to spark a debate in Parliament.
American businesses have begun severing ties with controversial pro-gun group the NRA in the wake of the latest mass school shooting.