"When you hire Shaun Edwards, you don't just get a defensive coach, you get someone who is unbelievable for your team culture."

After playing under Edwards with Wales, Tom Shanklin knows the impact the defence coach can have.

Since Edwards joined France's coaching team, that impact has been plain to see in Les Bleus' results with victories against England and Italy.

After spending 12 years with Wales, the 53-year-old Englishman returns to Cardiff on Saturday with a revitalised French defence.

Former Wales back Shanklin discussed how Edwards has helped France to impressive victories against England and Italy alongside ex-Ireland international Shane Horgan on Matt Dawson's 5 Live Rugby Show.

Here are the key areas in which Edwards has made a difference so far.

Immediate impact: 'France look so accomplished'

Shanklin: He made an instant impact when he came to Wales because we hadn't seen anything like it. We have seen an instant transformation in the way that the French team are colliding with attackers.

What you are seeing straight away is far more dominant tackles. You have to be fit if you want to defend the way he wants you to. There is so much running up and back continuously.

The big question is how fit are this French team? I think the way he wants them to defend is great for the first 60 minutes but they are starting to tire. It is going to be the biggest test for them in Wales.

Horgan: I can't believe how quickly he has impacted this French team. We know defences are where you can make changes quickest but he's only had a few weeks with this French team and they look so accomplished. The way they are operating is impressive.

Attitude: 'He gets that collective spirit together'

Horgan: France's attitude is completely different. You can see players are working for Shaun and each other. He gets that collective spirit together.

The scramble defence of Wales when he was coach was incredible. If you scored a try against Wales you really earned it. I saw that for the first time with this French team. Their work-rate on their scramble defence against England in the first week was really impressive.

Dawson: Shaun Edwards will be incredibly respectful of where he is coaching and the team they are up against this weekend. He likes to play, train and coach on the edge and will probably be battling this week around his emotions. He'll want to get it right for his employer but he has got to where he has got to because of Wales.

Cultural barriers: 'Unique way of introducing himself'

Dawson: The tricky part for Shaun is the cultural difference in France because he has a unique way of introducing himself to a new bunch.

He will be wearing the most horrific shiny shellsuit with probably not even matching trainers. He will be in the gym shadow-boxing himself. You can imagine the French players thinking, 'what on earth is going on here?'

Shanklin: He coaches with a lot of aggression, he's very animated in the way he does it. It's a lot harder to do that in France when you don't speak the language.

Intimidation: 'You don't want to let him down'

Shanklin: He's intimidating. You watch the games he played for Wigan in rugby league... When he first came over to Wales, we were all Googling 'Shaun Edwards' and we saw the red cards for Great Britain. He is like that as a person. You can see it through his emotion and his body language. Whatever he's doing it's working.

He instils that in you from the very beginning. Every single person needs to be in that defensive line no matter what's going on. You want to do it for him.

You don't want to let him down. You don't want to get picked on in analysis the following day. When you hire Shaun Edwards, you don't just get a defensive coach, you get someone who is unbelievable for your team culture.

What players and coaches say: 'He's a perfectionist'

France lock Bernard Le Roux: He's the most demanding coach I've had in defence. It's incredible what he does. He's a perfectionist who works very hard. At 30, I didn't think there was much I could learn in defence, but with him I learn every day.

France flanker Francois Cros: He tells us what we mustn't do. He gets angry. From the start, he arrived as he is and he hasn't changed. He's never been shy. He transmits to us his convictions and his burning desire to progress, to win, and we've seen that in the first matches.

France team manager Raphael Ibanez: We talked at the start of the week, we talked to each other. I just asked him what was the approach of the game, and if it was too much, maybe, emotionally.

Shaun is very professional - his reply was pretty clear. He just said 'my only focus this week will be to do my best for the players', and that's what he did, day in, day out. It was proper Shaun Edwards.

He has been very loyal to Wales and he loved coaching here. I just think we are very lucky to have him with us now."

How to follow live BBC coverage

Live coverage of Wales v France on Saturday starts at 16:00 GMT on BBC One, BBC iPlayer and the BBC Sport website.

Match commentary comes from Eddie Butler and Jonathan 'Jiffy' Davies, while Sonja McLaughlan will be pitchside with former Ireland captain Paul O'Connell.

You can also follow live on BBC Radio 5 Live Sports Extra and the BBC Sport website.

A peak audience of 8.4m tuned into BBC One for the Calcutta Cup game between Scotland and England earlier this month, with 1.2m also watching on BBC iPlayer or online.

Reach for this this year's competition on the BBC currently stands at 15.5m after only four live TV games.