(CNN) -- Decisive, confident, disciplined, straight-forward and intelligent. These are just a few of the mostly glowing words the U.S. State Department apparently had for Margaret Thatcher in 1975, according to an alleged cable that WikiLeaks published Monday.
Dated February 16, 1975, the cable attempts to explain this new rising star on Britain's political scene. At the time, Thatcher had just won control of the country's conservative party.
She became prime minister in 1979 -- the only woman to hold the job. Thatcher died Monday at age 87.
The cable is available along with a trove of others searchable on a massive database that WikiLeaks claims contains other U.S. documents. Several years ago, WikiLeaks became famous worldwide for publishing sensitive U.S. documents related to the Iraq and Afghanistan wars.
CNN cannot authenticate material on the database or the Thatcher cable itself. State Department spokesman Patrick Ventrell would not comment on it Monday.
As it appears in digital form on WikiLeaks' site, the cable says Thatcher "blazed into national prominence almost literally from out of nowhere" and that her ascent was remarkable because she then had "narrow range of prior experience." But Thatcher had captivated the public, the cable suggests, and was the "focus of intensive media and popular interest."
"There is general agreement among friends and critics alike that she is an effective and forceful parliamentary performer," the cable reads.
"She has a quick, if not profound, mind and works hard to master the most complicated brief. She fights her corner with skill and toughness, but can be flexible when pressed.
"In dealing with the media or with subordinates, she tends to be crisp and a trifle patronizing. With colleagues, she is honest and straight-forward, if not excessively considerate of their vanities."
The cable goes on to remark that Thatcher abides by the "courage of her convictions, and once she has reached a decision to act, is unlikely to be deflected by any but the most persuasive arguments."
She was, the cable adds, "the personification of a British middle class dream come true."
"The daughter of a grocer, she had by dint her own abilities and application won through, securing scholarships to good schools, making a success of her chosen career, and marrying advantageously."
The British leader had "conventional and somewhat forced charm, and above all her plummy voice stamp her as the quintessential suburban matron, and frighteningly English to boot."
The cable predicts what the future holds for Thatcher.
"If she is ever to become Britain's first woman prime minister, she must ... humanize her public image and broaden the base of her party's appeal," it says. "The odds are against her, but after her stunning organizational coup d'etat this past month, few are prepared to say she can't do it."
CNN's Elise Labott contributed to this report.