The former Wales and Lions captain - who retired through injury this time last year - has been assisting the Welsh Rugby Union in a plan to make sure the benefits of the World Cup are felt in schools across Wales.

This is less about rugby skills on the pitch, though, and more about learning and personal development in what is called a "WRU Digital Classroom" or "Dosbarth Digidol WRU".

The idea is to use rugby and the World Cup to assist with six areas of learning. They are: expressive arts; health and well-being; humanities; languages, literacy and communication; mathematics and numeracy; science and technology.

More than 250 primary schools have signed up and Warburton visited one of them - Ysgol Santes Tudful, in Merthyr - to help launch the programme.

Not only did the pupils show how they are using rugby in their all-round learning, but he was also given some fantastic good luck messages to pass on to his former teammates.

Afterwards, reflecting on what he admitted had been a moving welcome, the former Cardiff Blues player said he felt convinced that the power of rugby in Wales - and the impact it can have on children throughout the country - was something that was only now being fully harnessed.

"A lot of these initiatives can feel like they are just paying lip service, but going into classrooms and seeing reception kids running around with rugby balls - some of who may never have touched a rugby ball before - is very powerful," he says.

"So, too, is hearing them talk in group discussions about the emotions that rugby players are showing. It gives them confidence in talking about feelings and it's nice that rugby and the WRU can encourage that.

"These are the things that can make rugby a proper, national sport. It's not just about adults going to a rugby international match eight times a year. It's when everyone underneath gets rugby fever and then we can really call it a national sport.

"Whenever I go into primary schools, the first thing I talk about is being nervous and how that's okay. Kids see superheroes on TV, and think their sporting heroes are the same - that they are these emotionless, super-human people who don't get nerves.

"People think sports stars are impenetrable, but I always used to get nervous before every game. It was normal to feel like that, just as it's normal to feel nervous before a maths test.

"If we can make kids realise that nervous feelings are perfectly normal - that everyone gets them - then we can help them become more confident people. You don't have to be Iron Man to do something good in this world. You can be perfectly normal."