Alastair Cook keen to keep churning out the England runs

There was something perhaps approaching a tone of relief as Cook assessed his return, after his own record-breaking tenure, to what he unquestionably does best of all - scoring Test match runs for England.

Following a heartening debut victory over South Africa for the new captain at Lord's, Cook continues to be confident he and Root will work successfully together - and that the Yorkshireman will not have to radically change the chirpy personality so notable since his emergence as an international batsman.

"I still think you'll see the glint in his eye," Cook told the BBC in a sponsor's interview before the second Investec Test match at Trent Bridge.

"There will be moments when he'll still play that (cheeky) role at certain stages.

"With a bit of responsibility for those actions, you might think twice about doing it. But he still has that glint and smile in his eye, so I don't see it changing."

After shedding those leadership duties, Cook produced a crucial second-innings half-century as England opened the series with a 211-run win - with the help too of Root's 190 first time round.

"(As captain), you're thinking 'what will I do here if you win the toss?' - but (now) you don't actually have to worry about the consequences," he added.

"Those decisions you constantly have to make, getting judged on them all the time eventually can take its toll on you.

"So you certainly feel a bit more relaxed around the camp."

His switch back to the ranks, since his resignation in February, has had a liberating effect.

"Naturally without having to make all the decisions, you are going to feel a bit freer.

"It's been an interesting seven months, a rollercoaster of emotions - certainly in January and February.

"It will be the same for Rooty, unfortunately (one day) - once you're England captain, you're always going to be a former England captain."

Cook has had to come to terms with that, but appears content.

"I understand why people want to talk about it, because it is interesting to see the new captain and the old captain still in the side," he said.

"But I hope my personality and relationship with Joe (means) we shouldn't have any problems.

"As he feels more comfortable in the role, and I feel more comfortable, I will maybe throw a few more suggestions in."

There is a familiarity in their role reversal.

"In the first Test match, we both stood at first and second slip and it was me bouncing ideas off Joe and him deciding which idea he might take or not," Cook added.

"Go back a year, and it was him giving me the ideas - 'What do you think of this?' - and me making decisions.

"I was just pleased for him, because he got off to a good start, and actually I was very impressed with the way he handled himself."

Root has not made what Cook believes might have been an understandable mistake, to spell out his mission statement in a grand dressing-room speech.

"After those months of knowing he was going to be captain, (you might think) he'd come in and say 'you've got to do this, got to do that' - and I reckon that's probably the worst thing you can do," the 32-year-old said.

"By playing it a bit more low-key, his message will grow and get clearer and stronger as he goes.

"You often see a captain who comes in and thinks he's got to do this at the start of his reign, this is what he wants ... and you've forgotten everything he said after two minutes.

"Because he didn't do that, everybody was still waiting for it - and when he does speak, he's very clear and precise in what he wants to do."

Cook is pretty focused too - to carry on as long as possible piling up more runs than any other previous England batsman.

"I hope so," he said.

"I was asked about captains sometimes struggling back in the ranks for motivation, but I genuinely love playing cricket.

"Whether it's an Essex or an England shirt, I genuinely love trying to score runs and set up runs for the side.

"I hope I can be part of it for as long as possible, because one day some bloke will tap me on the shoulder and say 'We don't want you any more ... you won't get the opportunity to score those hundreds'.

"Not many people get to choose, but I hope it's a few years off yet before the dreaded tap comes on that shoulder."