The Iron Lady is auction gold.

Speeches, books and outfits belonging to late British Prime Minister Margaret Thatcher — including the Iron Lady's wedding dress — have soared above their estimated prices at a London auction.

Christie's is selling 150 lots Tuesday, and a further 200 in an online auction that ends Wednesday.

Thatcher's red prime ministerial dispatch box sparked a bidding war and sold for 242,500 pounds ($365,000). It had been estimated to reach between 3,000 pounds and 5,000 pounds.

A signed copy of the speech Thatcher made on becoming Britain's first female prime minister in 1979 — declaring "Where there is discord may we bring harmony" — sold for 37,500 pounds ($56,460). Her 1951 wedding dress fetched 25,000 pounds ($38,000).

Thatcher died in April 2013, aged 87.