Churchill, who was 74 when these 1949 shots were taken, is heard observing that the test will help him understand how "this thing they call TV is going to make its way in the world," TV officials told The Daily Telegraph.
The former war-time British Prime Minister, then leader of the opposition and no TV fan, confined most of his broadcasts to the radio.
The video, released by the British film Institute, also showed future Prime Minister Margaret Thatcher making a pitch for the housewives' vote.
"You know men have not made such a success of it all the time," she said. "So, to yesterday's men, tomorrow's women say hello."