Cricket: 'A phenomenal moment in cricket history' - Blackcaps blown away by outstanding Devon Conway debut

"Phenomenal" - that's the main takeaway from Blackcaps batting coach Luke Ronchi after debutant Devon Conway became only the seventh batsman to score a double century on his test debut.

After Kane Williamson won the toss and batted first at Lord's in the first test against England, 29-year-old Conway ticked test cricket off his list of international to-dos, and did so in style, playing out of position as an opening batsman.

On opening day, Conway became the 12th New Zealander to reach triple figures in his first test match, before kicking on to turn that into a double ton - just the second Kiwi to do so after Mathew Sinclair (214) in 1999.

By the time he was finally out, Conway had scored an exact 200 of New Zealand's first innings total of 378.

Speaking to the AM Show after the day's play, Ronchi hailed Conway's effort, proving his class yet again, this time in the game's toughest format.

"Phenomenal. It's so cool to see someone come in, and the way he's taken to international cricket - it's a heck of a load harder than he's making it [look].

"To score a double hundred in test cricket for anyone is difficult, but to come out, your first innings, at Lord's and to play the way he did on that surface was just phenomenal.

"I think the way he'd been going, almost every shot of his had worked out the way he'd wanted it to.

"It got a bit nervous before he got to 100 and before he got to 200 just because you want him to get there. When everyone saw it go up, [we were] sort of jumping around a little bit to see what had happened.

"We all saw the fielder signal 'six' before anything else, so then we were all jumping around and cheering and clapping so it was a phenomenal moment in cricket history."

The double century is just the latest of Conway's impressive outings in a Blackcaps jersey.

Over the course of the New Zealand summer, Conway took to international cricket like a duck to water. In his 14 T20 Internationals, Conway scored 473 runs at an average of 59.12 with a best of 99 not out against Australia.

In one day internationals, Conway scored 225 runs from three games at an average of 75 and a best of 126 against Bangladesh.

Those numbers did nothing to quell the hype around Conway, who'd been forced to wait four years to qualify for New Zealand after migrating from South Africa but dominated domestic cricket for Wellington in the meantime.

And Ronchi says Conway's previous success at every level he'd played at left the Blackcaps confident he'd succeed in that final step up to test cricket.

"[When] you do what he's done domestically, and in the white-ball season at home, he's been phenomenal. 

"From our point of view, we know what he can do, what he's capable of and how he goes about his cricket. 

"When someone is that well prepared to go into a test series and a test match, you let them go about their business as much as they possibly can, that's when he works best. If his mindset is where he wants it to be, where he needs it to be, you see some pretty amazing things from the man."

As for Conway's future, Ronchi adds that for now, he'll have to stay at the top of the order, despite being earmarked to slot in at No.4 in the batting order when Ross Taylor calls time on his illustrious career.

"That's the position for the time being, there's no other position really. I don't see why that's going to change any time soon."

The Blackcaps finished day two with England on 111/2, 267 runs behind in the first innings.