British and Irish Lions 2013: Gatland's squad has the X factor

So after the endless speculation and selection parlour games, what to make of Warren Gatland's 2013 British and Irish Lions squad?

If around 30 of the names unveiled on Tuesday were predictable enough, the identity of the last half-dozen or so still provided plenty of intrigue and, in some cases, surprise.

Gatland's 37-man party contains a balance of experienced old hands, talented young thrusters and players with the required 'X factor' to provide something a little bit different.

Brian O'Driscoll will deservedly become only the third player ever - and the third Irishman - to go on four Lions tours. Two other legends, Willie John McBride and Mike Gibson, both made five.

Ireland's Paul O'Connell and Welshman Gethin Jenkins are summoned for their third tour of duty, while nine other players will be embarking on a second Lions adventure.

One of them, Matt Stevens, was the closest thing to a 'wildcard' selection, even though the prop has toured with the Lions previously, in 2005. He is the only member of the party not currently playing Test rugby, having retired from England duty last summer to spend more time with his young family.

At 30 he is still relatively young in rugby terms, more so given his enforced two-year break from the game in 2009 after testing positive for cocaine while at Bath.

The Lions could have chosen another pure set-piece tight-head specialist such as Ireland's Mike Ross or Scotland's Euan Murray to back up the frontline choices Adam Jones and Dan Cole, but the "all-round game input" - as Lions forwards coach Graham Rowntree put it - of Stevens's ball-carrying and offloading skills swayed it.

The South Africa-born prop, who returned to rugby with Saracens in 2011, is also the sort of colourful character - former Celebrity X Factor finalist, coffee-bar entrepreneur - that tends to thrive on a Lions tour.

"He is very popular within any team environment, and is a good tourist," Gatland said.

Stevens's Saracens team-mate Mako Vunipola was another whose "points of difference" - the phrase of the day among the coaches - proved decisive, securing him the other available spot in the props department. Gatland has summoned plenty of power to the task of winning down under, but on hard, fast grounds he also needs forwards comfortable with a mobile, offloading game played at speed. And not many 20-stone props fit that bill.

With Richard Hibbard providing scrummaging ballast and Tom Youngs dynamism around the field, Dylan Hartley's "aggressive edge"- and superior line-out accuracy - gave the England man the nod over Ireland's unfortunate Rory Best for the third hooking berth.

If the front-row fraternity were the main points of interest among the forwards, the balance of options among the backs - particularly in midfield - was also a hot topic.

Will two fly-halves be enough? The rationale behind it is sound enough: if you take three specialists, trying to give everyone enough game time to stake a claim for the most pivotal role actually works against the main objective - making sure everyone is fully tuned up before the first Test in Brisbane.

With only six games beforehand, Jonny Sexton and Owen Farrell will probably play no more than three games each anyway.

"We want to accelerate that preparation by giving Jonny and Owen the best opportunity to navigate a Lions team around the park," explained backs coach Rob Howley.

But when it came to nominating the player who would most suit the role of a 'utility' back able to cover several positions including 10 - James Hook? Billy Twelvetrees? Ian Madigan? - not many pundits had Stuart Hogg, the baby of the party, down in that capacity.

The 20-year-old flier made his Scotland debut on the wing, scored a couple of sensational tries from full-back in this year's Six Nations, and has also played outside centre for his club Glasgow, but has little or no experience at 10.

"He has that X factor about him, whether as a full-back or at 13," said backs coach Rob Howley. "I think he can play 10 as well. There is something about the magic of the Lions jersey and there may be an opportunity where he might play 10 and can cover that."

As well as limiting the squad's frontline goal-kicking options to the two fly-halves and full-back Leigh Halfpenny, the absence of a Hook or Twelvetrees is more surprising given that Jamie Roberts is the only specialist inside centre named. But Gatland appears comfortable with the option of also using either O'Driscoll or Jonathan Davies, both more accustomed to the 13 jersey, at 12.

Sean Maitland, the New Zealand-born Scot whom Gatland selected for Waikato while still a schoolboy before he moved on to the Canterbury Crusaders, may be the least experienced player in the party, with only five caps to his name.

But the 24-year-old impressed sufficiently with his all-round rugby intelligence during his debut Six Nations campaign to claim the final wing berth ahead of the likes of Ireland's Simon Zebo, Scotland team-mate Tim Visser and England's Chris Ashton.

"He doesn't make a lot of mistakes," Gatland said. "He is a big man who can run sub-11 seconds for the 100m and has experience of playing Super Rugby in Australia."

Wales, as predicted, have their biggest contingent on a Lions tour since the 16 initially chosen in 1977, but there was little argument about any of those picked, with only fly-half Dan Biggar - of the side that humbled England in Cardiff - missing out.

Flanker Dan Lydiate may have only played four games since returning from a broken ankle, but Gatland's admiration for the 2012 Six Nations Player of the Tournament is well documented, and the first Test against the Wallabies is still seven weeks away.

The blind-side bruiser's punishing defence marks him out from the other options in that position - similarly the athleticism and line-out prowess of Englishman Tom Croft, and Irishman Sean O'Brien's ball-carrying and work-rate. With captain Sam Warburton also able to play at six, it is conceivable that none of those three might even make the Test side, with Justin Tipuric's creative instincts offering another enticing option at open-side.

The back row was always going to provide some notable casualties, with two national captains - England's Chris Robshaw and Scotland's Kelly Brown - among those to miss out.

Robshaw "was desperately, desperately unlucky," according to Rowntree, who admitted he faces a "difficult conversation" with the Harlequins man about his exclusion. "I feel for him because he has been exceptional. But I would like to think if we have an injury we would go straight for Chris."

And therein lies hope for those missing the initial cut. Robshaw is still a reasonable bet to make it to Australia, with an average of five replacements being summoned over the past four tours and four of the original party not even making it onto the plane to South Africa four years ago.

With two pre-tour training camps, in Wales and Ireland, scheduled over the next few weeks, and at least 23 of the squad involved in Premiership and Pro12 semi-finals and finals before departure on 27 May, the chances of all 37 making it to Australia in one piece are slim.

The squad announcement is just the start of the process. Whatever Test team you might like to pick now, the side that steps out at Brisbane's Suncorp Stadium on 22 June is just as likely to include someone who is not even invited to the party yet.