Brendon McCullum reveals Kevin Pietersen was 'shocked' when he was offered England coaching gig - and wants the outspoken legend to 'challenge' his methods after previous criticism

Brendon McCullum has admitted Kevin Pietersen was 'shocked' when he first asked him to join England's white-ball set-up as a batting mentor.

Pietersen joined up with the squad in Southampton on Sunday ahead of Tuesday's first T20 against Sri Lanka at the Utilita Bowl – the first of six limited-overs games in 13 days – and has been encouraged by McCullum to 'challenge' any aspect of the dressing-room's culture.

His appointment comes less than two years after Pietersen criticised England's training schedule during a white-ball tour of India, saying he was 'absolutely gobsmacked' that nets had been cancelled before the last two ODIs. He later described the situation as 'absolutely disgraceful'.

Those comments cropped up when McCullum first contacted Pietersen, who averaged 40 during his 136 ODIs for England and helped them win the T20 World Cup in 2010.

'That was one of the first things we talked about,' said McCullum. 'He said: 'Gee, I was just criticising you not long ago.' I said: 'I don't care about that. Some of it's fair and some of it would need some explanation, but I have no problem with that.'

'It's healthy when you create an environment where you're able to challenge. That's one thing I want him to do. It's not just bury himself in the batting per se, but look across the entire environment, and if there's anything you pick up then just come and challenge me on it.'

Meanwhile, McCullum has urged fast bowler Brydon Carse to 'get his house in order' following his arrest outside a Derby nightclub last month – and reminded other players of the price they may pay if they make headlines for the wrong reasons.

'I hope it's crystal clear what is expected, not just of this group, but of those who have got aspirations to play for us,' he said. 'There is a lot of talent around, if you're not prepared to do that, there are other guys who will be given those opportunities.

'I've spoken to Carsey a lot and it's the same message. You need to make good decisions off the field that allow you to be able to be the best version of yourself. As far as Carsey is concerned, it's a good chance for him now to get his house in order and then push for selection for the next opportunity that arises.'