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  Jeremy Guscott, Jonathan Davies, Keith Wood and Andy Nicol have 191 Test caps - including 13 for the British and Irish Lions - between them.
  They will be on your televisions and radios analysing all the action from the 2017 tournament - but we've nabbed them first to find out who they expect to win, and plenty more besides.
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  Former England centre Jeremy Guscott: England are the reigning Grand Slam champions and have won 13 out of 13 under Eddie Jones, but being realistic they haven't taken teams apart with amazing attack. It's been very much brutal defence that's been giving them the edge and improved fitness. They may need to produce more than that this year.
  Ex-Wales fly-half Jonathan Davies: Wales will have to perform better defensively - and more importantly offensively - if they are to be contenders this year. They also need to have more variety in their game.
  Keith Wood, former Ireland hooker: Ireland are looking very good at the moment. The coaching seems to be a little more flexible than it has been and the team seem more comfortable, with the current gameplan suiting the expanded squad.
  Former Scotland scrum-half Andy Nicol: Scotland are in pretty good shape - they are definitely improving, with a well-balanced team and good coaching. There is confidence throughout the squad after a positive autumn, as well as Glasgow qualifying for the knockout stage in Europe. My target for them is three wins.
  JG: It's between England and Ireland. England have three home games (and I expect them to win all three), which gives them a slight advantage, but that is countered with having to play Ireland away. Ireland are playing at a tempo and intensity that the rest of the Six Nations haven't reached yet, and I expect them to win the championship.
  JD: It's got to be Ireland. However, I don't expect them to win the Grand Slam (winning all five of their matches), so bonus points - introduced this year - will be important.
  KW: I expect Ireland to win. It is the right cycle of games for them, their confidence is high and the provinces are doing well in Europe. They also have a small injury list - notwithstanding Johnny Sexton's absence from the opening weekend - and more strength in depth than before.
  AN: England and Ireland start as favourites, with not much between them. They meet in the last game in Dublin with home advantage being crucial and probably the difference between the two. The style that England play and their ability to score more tries and points make them my favourites to win the Six Nations on points difference - or bonus points - but with no Grand Slam.
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  There are two main changes this year - stricter rules on high tackles and the introduction of bonus points.
  The former means anyone making contact with the head of an opposition player, either recklessly or accidentally, will be punished more severely.
  The introduction of bonus points brings the Six Nations in line with other competitions around the world and means sides scoring four tries, or losing by less than seven points, will earn bonus points.
  JG: The new rules on high tackles will have the biggest effect. Without doubt players will be going to the bin for high tackles and that will have a bearing on results for sure.
  JD: The new high tackle ruling and the way each referee interprets each incident.
  KW: High tackle rule. The margin between a correct tackle and a high hit is too small.
  AN: The new high tackle law could see more yellow cards, which could influence games. I'm not sure bonus points will come in to it - certainly not in first few games.
  AN: England's Owen Farrell. Tactician, kicker, intense, brave, winner - there's five words I'd use to describe him.
  JD: I pick Farrell too - he is key to England's game management.
  JG: Ireland back rower CJ Stander - great work-rate and explosive ball-carrying.
  KW: Ireland scrum-half Conor Murray - he leads by deed and composure.
  The Six Nations began as a four-team competition - the Home Nations Championship - in 1883 before adding first France and then Italy - the latter in 2000.
  The growth of rugby union over the past decade has seen Georgia, in particular, and a resurgent Romania become competitive at the highest level, but unable to move up from the second-tier Rugby Europe Championship because there is no promotion and relegation.
  The second tier nations have called for the chance of admission to the Six Nations but the chances of that happening in the "Short to medium term" are unlikely, according to the tournament's boss John Feehan.
  AN: I am not in favour of straight relegation from the Six Nations but I am in favour of a play-off between the bottom team in the Six Nations and the top nation in the Rugby Europe Championship. Georgia have earned the right to have a shot at making the top level having won the Nations Cup (the Rugby Europe Championship) in eight of the past nine years.
  JG: I'm not sold on relegation yet. It may come in the future, but I've not heard enough compelling evidence to make a change yet.
  JD: I think the bottom team in the Six Nations should take part in a two-game play-off against the top candidate.
  KW: No, but we need to see these teams - the likes of Georgia, Romania and Russia -  play tier-one teams more often.
summary: We have asked four wise old heads what they expect to happen over the next seven weeks in the Six Nations.