Question: will you watch if the prize is right?

Cuddly Toy. The Blankety Blank Cheque Book and Pen. Come On Down. Can I Have A "P" Please, Bob? The familiarity of these phrases is testament to the impact quiz shows have had on the popular consciousness since their inception in the 1950s. There's no denying that Joe Public, sweating under the studio lights as he racks his brains for some obscure fact that will reward him with an exotic holiday or a new car, makes gripping television.

It was ITV that came up with the first British shows to offer a cash prize - Take Your Pick and Double Your Money - in September 1955. And it was the same channel that last week announced the autumn launch of Who Wants To Be A Millionaire?, the first TV quiz to offer prize money of up to pounds 1m, if contestants are able to answer 21 general knowledge questions correctly. Presumably referring to the weekly creation of millionaires by the National Lottery, ITV programming director David Liddiment says: "The days of winning a car are long gone. You now need to offer much, much more than that."

Of course, there has been the usual harrumphing about the morality of giving away such huge sums of money on television. Teachers have expressed concern that shows give children the wrong idea about the value of money, and traditionalists have waxed lyrical about the days when contestants were happy to go home with a food mixer or a toaster, citing the idea as another ugly symptom of the instant wealth culture created by the National Lottery.

But the arrival of the pounds 1m quiz show seemed inevitable. In the Seventies, the amount that any one show could give away was limited to pounds 6,000, but since 1990, when that limit was lifted by the Broadcasting Act, prize money offered has soared. Bob Monkhouse's $64,000 Question was the first to push the envelope, offering pounds 6,400; Shane Ritchie's Lucky Numbers took the figure to pounds 20,000, and Bob Holness's Raise The Roof gave contestants the chance to win a pounds 100,000 house. And, of course, pounds 100,000 cash is currently up for grabs on the BBC's new Saturday night National Lottery Big Ticket show, which Who Wants To Be A Millionaire? is no doubt intended to eclipse.

As Bob Holness, veteran presenter of, among others, Blockbusters and Raise The Roof, points out, these amounts are not so remarkable when considered next to to those being given away on American television four decades ago. It was on American radio, in the Forties, that the cash quiz was born, with The $64,000 Question, and when it moved on to CBS TV in 1955, it prompted a wave of imitations on which it was possible to win six-figure sums. One of the most successful was Twenty-One, the scandal surrounding which was related by Robert Redford in his film Quiz Show (1994).

But some of our most popular quiz programmes offer barely any reward beyond a piece of cut glass and the kudos of having competed. University Challenge, launched in 1962 (admittedly with a rest between 1987 and 1994), and Mastermind, which ran for 25 years, became national institutions.

"It's the format and the competition that attracts the viewer," asserts William G Stewart, presenter of Fifteen-to-One and the man who brought The Price Is Right and Family Fortunes to Britain from America. "It most certainly isn't the size of the prize - all attempts to make the prize the attraction have failed. The evidence for this is Raise The Roof, in which they decided they would give away a house as a prize and then tried to find a format that would allow them to do that. But the format was boring, and the programme's no longer on the air." Stewart was also executive producer of Don't Forget Your Toothbrush when it was launched, the success of which, he says "had nothing to do with the prizes. All Chris Evans gave away was a holiday, and the holiday for two in Barbados has been the staple diet of TV shows for time immemorial."

Bob Holness agrees. "I think the format is desperately important," he says. "I do think audiences are attracted by enormous figures, which is why the Lottery has been so successful, but if the idea is not entertaining, it won't keep the viewers." So what formats have caught the public imagination over the years? Stewart points to Family Fortunes, which has been running since 1979, and The Price Is Right, which knocked Coronation Street off the top of the ratings in its early days. "Most of the others seem manufactured, and don't seem to have a natural reason for being around."

With regard to Who Wants To Be A Millionaire?, Stewart thinks there will almost certainly be a big audience for this new show in the first couple of weeks, when people are just wanting to see people win pounds 1m. "But then people will just read about it in the papers the next day. It's what happened with the original Lottery show on the BBC. The idea was that the programme would attract 15 million viewers a week because people wanted to know if they themselves had become millionaires. But, in no time at all, the Lottery audience dropped off, because the programme was rubbish.

"It seems to me that ITV are starting with what they're going to give away, and then build the programme around it. But if they discovered a great format, then they wouldn't have to give away pounds 1m to attract an audience. My instinct is that it won't work: it's just all hype."

But David Liddiment remains bullish about the project, despite this apparent lack of faith. He feels the pounds 1m prize will be the attraction only indirectly, in that it will "heighten the drama, and up the stakes". Quiz shows generally fall into two camps, he says: those in which the quiz is used as a springboard for an entertainer, such as Bruce Forsyth or Michael Barrymore, and those where "the game's the thing", like Mastermind or The Krypton Factor. This show, he claims, falls into the latter group.

But the stakes seem high in more ways than one. Although it has taken out insurance to stop too many people reaching a position where they are able to win pounds 100,000 or more, isn't ITV worried that, at the other extreme, not enough contestants will be prepared to gamble already substantial winnings to get to that much-hyped million? Liddiment admits that until the programme is actually made, "we won't know all the answers. But it will be interesting to see how people deploy their tactics."

Whether the masses huddled at home in November will be similarly interested remains to be seen. Otherwise, the show may fall from favour as quickly, albeit not so ignominiously, as Twenty-One.