Nothing is agreed until everyone is agreed

Name that Lions squad. From the guess list to next week's guest list, it's certain the 37-man squad for the OZ odyssey this summer will change by the fortnight as the championship unfolds. Why, even the Lions management are at it: although they will issue about 70 initial invitations in the next 10 days, they have covered their options by saying that the final 37 probably won't be drawn exclusively from that initial list.

It happened last time: Peter Clohessy, for one, was not even on the original invitation list, then made the cut only to miss the tour with his nagging back problem. Between now and the mid-April announcement of the touring party, favourites will lose form or fall down injured and players who are now not even in their national squads will emerge as candidates.

The final say rests with coach Graham Henry, manager Donal Lenihan and assistant coach Andy Robinson, though they will be assisted along the way by those co-opted from the home countries onto the selection panel: Derek Quinnell (Wales), John O'Driscoll (Ireland), Ian Lawrie and John Rutherford (Scotland) and Simon Halliday (England).

The accompanying list is no more than a rough guide toward the current pecking order. You could make a case for a good deal more. Most probably there is an elite of about 22 players whose form and proven ability means they've already one foot on the plane to Perth - barring serious injury or a sudden loss of form. It's the last 15 positions where the real individual battles will be conducted.

Some positions or combinations are a good deal more competitive than others. But full back and tighthead prop (where the dearth across Ireland and Britain is quite striking), are probably the cause of most concern for the selectors.

Welsh concern over the full back position for this Saturday's opener against England highlights the problem. With Shane Howarth ruled ineligible, Matt Cardey out of form and favour at club level and Rhys Williams suffering a crisis in confidence, Wales have gone with the solid if stolid outhalf Stephen Jones for his first game at full back in three years as a stop-gap measure.

England's Matt Perry, who would have looked the leading candidate throughout last season and the early part of this, may be paying the price of so much continuous top-flight rugby in the last four years. Then again, his omission from the Wales match may help to rejuvenate him. Iain Balshaw is inexperienced, but his potential and his selection by England for Saturday immediately shoots him up the ladder.

At tighthead, the absence of an outstanding candidate means John Hayes is being mentioned in dispatches, even by some of the most ardent critics of his scrummaging technique.

Of the prime Irish candidates, Keith Wood and Brian O'Driscoll are top of the pile, and Malcolm O'Kelly is just behind them for what may be the most competitive area of all at second row. O'Driscoll would probably need only one club game in early April to make the cut, with Henry grateful for any reduced workload for this thoroughbred. Nor should Denis Hickie's absence this Saturday harm his chances, given how he recovered last autumn, and his form in the last three or four games should be enough to earn him his plane ticket.

Ronan O'Gara is fast emerging as a serious contender for one of the three outhalf slots, although he might have some elbowing to do given Jonny Wilkinson and Neil Jenkins look near certs and the versatile Gregor Townsend is a past Lion. But O'Gara is on a rich vein of form and deserves a few 80-minute runs for Ireland this time around.

At centre, Rob Henderson, due to his fitness, form, understanding with O'Driscoll and proven abilities as a high-impact weapon off the bench, has to be one of the fringe contenders. Likewise Shane Horgan, with his physique and versatility.

Peter Stringer needs a good championship, as his autumn form may have set his candidature back a bit in an area where Matt Dawson, Kyron Bracken and Robert Howley are all vastly more established.

Peter Clohessy would love a valedictory Lions tour, and should make it if his body holds up. Mick Galwey and Jeremy Davidson must first vie with each other and then confront a highly competitive list of locks.

The more you look at the blindside flank alternatives, the more you realise Simon Easterby would have had a great chance barring injury. The same is true to a slightly lesser extent of Kieron Dawson. He might yet come back into contention, though it will be a big ask. With so much competition from England, Wales and Scotland in the back row, even the Shannon trio will have to go some over the next five games.

England are bound to provide the greatest number of players, and should make up the guts of half the squad. Accordingly, the barmy army will travel with gusto again. Already 8,500 British and Irish supporters have booked their flights, a figure likely to rise to around the 10,000 mark. And don't forget the expatriates who like their Christmas turkey barbecued.

The old championship, given further lustre by the advent of the Italians, hardly needed it anyway, but as with all Lions years, an already spicy dish has been given added flavour. It'll be fun alright.