The program was conceived by the BBC as their way to fill the space created by the then-recent relaxation of the rule of the "toddlers' truce," when television had previously closed down for an hour to allow parents to see their children off to bed. As such, Tonight went out to a new and untried audience, an audience who, at this time of the evening, would be quite active rather than settled, who would be busy preparing food, putting children to bed, or getting ready to go out. Tonight was designed around the needs of this audience, and its style reflected this: the tone was brisk and informal, mixing the light with the serious, and items were kept short, allowing audiences to "dip in" at their convenience. This emphasis on the needs of the audience was something of a departure for the BBC. which had tended to adopt a paternalistic tone with its viewers, giving them not what they wanted but what they should want. Tonight was going to be different. It was not to talk down to the viewer, but would, as the Radio Times put it, "be a reflection of what you and your family talk about at the end of the day." In Baverstock's words, Tonight would "celebrate communication with the audience," and, indeed, the program came across not as the institutional voice of the BBC but as the voice of the people.

     Tonight was recognized by many to be evidence of the BBC's fight back against the new Independent Television (ITV) companies that were quickly gaining ground and by 1957 had overtaken the BBC (which was still broadcasting only one TV channel), with a 72 percent share of the audience. But if Tonight was largely a result of competition and the breaking of the monopoly, which in effect forced the BBC to adopt a more populist programming philosophy, the style and content of the program also reflected broader social and cultural changes. Tonight seemed to capture an emerging  attitude of disrespect  and popular skepticism toward institutions and those in authority. Furthermore, the adjectives that were often used to describe the program at the time, such as "irreverent," "mod­ em," and "informal," could have easily described the mood that was beginning to inform other areas of the arts and popular culture in Britain at that time.

     Tonight introduced a number of innovations to British television. It was one of the first programs to editorialize and adopt a point of view, flaunting the public-service demands of balance and impartiality. The program also introduced a new (some might say aggressive) style of interviewing, where guests would be pushed and harassed if it was thought they were being evasive or dishonest. Tonight eschewed the care­ fully prepared question-and-answer format that had prevailed in current affairs programming until then. Furthermore, broadcasters had tended to fetishize the production process, concealing the means of communication and carefully guarding against mistakes and technical breakdowns that threatened to demystify the production. Tonight, however, kept in view such things as monitors and telephones. Its interviews were kept unscripted and any technical faults or mistakes were skillfully incorporated into the program flow, giving Tonight an air of spontaneity and immediacy.

     Tonight was meant to be a temporary response to the ending of the "toddlers' truce," and was initially given a three-month run. It quickly proved popular, however, and within a year was drawing audiences of over 8 million. In addition, the program won critical acclaim, receiving the Guild of Television Producers Award for best factual program in 1957 and 1958. The program generated other material as well, including feature­ length documentaries, and was the inspiration behind That Was the Week That Was, a show  that stepped up Tonight's irreverent, hard-hitting approach for a late­ night adult audience.

     Baverstock left Tonight in 1961 to become assistant controller of programs, and his place was taken by Alasdair Milne. Milne proved to be a capable editor and indeed oversaw a number of innovations, including the feature-length documentaries.

     However, the program would not be the same without Baverstock, whose leadership and vision had made Tonight something of an individual success. By 1962 it was argued that the program had become rigid and stale. As is the case with many innovative and groundbreaking enterprises, the program could not sustain the pace of its initial inventiveness. The final edition went out in June 1965. Nevertheless, in its eight-year run, Tonight had established a format for current-affairs programming that mixed the light with the serious, which blurred distinctions between education and entertainment, and which managed in the process to soften the image of the BBC, transforming it, as Watkins has noted, from an "enormous over-sober responsible corporation," to something that looked "more like a man and a brother."