It hasn't been done before in the Six Nations and it was extremely rare when it was just the Five Nations. France won it four times on the trot between 1959 and 1962 but the 1960 win was shared with England. Back then two teams with the same number of points at the end of the season shared the title, unlike now when points difference (scored minus conceded) divides the tied teams. Which was what happened last year when Ireland edged England and Wales.
And Scotland did it in 1925-27, sharing two titles with Ireland.
So what of this year? England are the bookies' favourites despite the fiasco of the World Cup last year. I still haven't worked out how they contrived to lose to Wales, not that I'm unhappy with that result given my ancestry. But a computer programme that was pretty successful in predicting the World Cup results says it will be Ireland again this year. And again on points difference from England. It could go down to the wire with England facing France in Paris, Ireland playing Scotland at home and Wales taking on Italy in the Millennium Stadium on the final day.
So bookies or computer? The bookies rarely get it wrong; they can't afford to. But neither they nor the computer are infallible.
Wales and Scotland were desperately unlucky not to make it to the semi-finals of the World Cup, unlike Ireland, who were convincingly beaten by Argentina in the quarter-finals, and England, who didn't make it past the first round.
France were hammered by the All Blacks and it remains to be seen whether they have recovered from that while Italy look like being the whipping boys again even if they did manage to push Scotland into the wooden spoon spot last year.
So: CAN THEY DO IT?