Make no mistake, I would love to be out in South Africa in that Lions squad. But then again, who wouldn’t want to be in that squad?

But this is what I am thinking when I am imagining being around this Lions squad. I am not thinking: “Poor me, I wish I was there.” I am asking myself: “How close, how tight are they as a squad?” And: “Will the Test team be looking around at each other in the dressing room before tomorrow’s game thinking, ‘I respect you and I will put my body on the line for you’?”

Because the success of the Lions, for me, rises or falls on the trust and the bond that are built. And I know that’s a Lions cliché, so I will rewind to this time four years ago, to the first Test against the All Blacks in Christchurch, and use that horrible, wet night to explain.

Building up to that Test, there were a lot of nerves. The quality of the sides that we had played in the build-up games made clear the quality of the opposition that we would be facing. And let’s not take anything away from those All Blacks, they won 21-3 and they were superb, but the foundations of the Lions’ defensive game fell away that night and it was trust — or lack of it — that was the cause.

Defensively, it felt that night as though the All Blacks were a threat from everywhere — from wide, from the blind side, through the middle. We ended up trying to plug holes, but that became like the leaking ceiling: you put a bucket down to catch the drip, but it just comes through elsewhere. And that was a day when it poured. I remember three or four occasions when I was covering out wide and thinking: “We’re three, four, five players short here.”

Because when the trust in the team has gone and your team are under threat, you immediately think: “I’d better go and help.” So you move to the immediate area of threat. But all that does is move players out of position. If the attacking side then switch the point of attack to where you have come from, then you are suddenly one man short.

As soon as you start playing individually like that, rather than as a team, your problems escalate. Every individual in a Lions shirt that night had that hopeless feeling: there’s nothing I can do. That is why faith and understanding and trust are essential to making the Lions work. And it has to go beyond being friends and getting on, it has to go so much deeper so that — unlike in 2005 — it can withstand the first moment the proverbial s*** hits the fan.

All teams that have achieved high levels of success will have known what it is like to defend on your own line, that do-or-die, all-for-one, body-on-the-line experience. Now, it is hard to do that after ten years together — that’s ten years of getting to know your team-mate, knowing that he will make the tackle, that you can trust him to make the tackle, knowing that you don’t have to cover him because he can cover his own turf. That is what the trust, as a defensive unit, is about, and that is a trust built over years of experience together.

But then you go away with the Lions and you have to build the trust in a few weeks. Then it becomes a different trust, a trust built on faith. That faith becomes the glue and it has to hold up under extreme pressure.

I would be the first one to admit that, in that fateful first Test on that Lions tour four years ago, my faith wasn’t strong enough. You think: “Oh, s***, they’re breaking left, I’ll cover left. And then, in a split-second, you’re thinking: “Oh no, they’ve broken right and I’m out of position.” There is another cliché for playing rugby like this; it’s called chasing shadows.

Defence is so hard on a Lions tour. One of the joys of the Lions is playing with some of the greatest attacking players in the world — that is what it was like for me playing with Jason Robinson in 2001 and what it must have been like playing with John Bentley in 1997 and it looks as though that is what it is like playing with Tommy Bowe this time.

The joy of an attacker is that he can beat three men on his own. The problem with defence is that you might be the greatest tackler, the greatest reader of the game, but you cannot beat three attackers. You cannot stop a three-on-one. Attack is often based on freedom. Defence has to be more ruthlessly systematic.

That, for me, is partly why the Lions do all those team-building exercises, to short-cut the knowledge that grows from working together and instil a level of faith in its stead. In a way, it’s a bit false, but when it works it’s wonderful.

I played in one other first Lions Test, against Australia in Brisbane in 2001, and the faith must have worked because I remember standing next to Brian O’Driscoll, Dafydd James, Scott Quinnell — players I’d barely known a few weeks beforehand — and feeling as though I’d been playing with them for five years. I also remember feeling nervous, more nervous than ever in my life, certainly more nervous than before the World Cup final 2½ years later. And I suspect that this might have been because our team — as any Lions team must be — was built on faith rather than years of knowledge and shared experience.

When I played for England in 2003, you knew where you stood. You knew that, at best, your performance could hit nine or even ten out of ten, and that, at worst, it would go to seven or even a six. But it could never spiral to anything worse than that. With the Lions, so much of your preparation work is to stop the downward spiral. Getting to know each other, building the trust — that all goes towards preventing your bad days becoming worse than a seven or a six out of ten.

But I guess I felt so nervous before Lions Tests because you don’t really know your team, do you? You can’t. Not like your club or your country, as we showed in Christchurch that night when we did spiral downwards. So that is why I hope the Lions feel close and tight. Because tomorrow they will need that faith to be their glue.