Alastair Cook: Brave skipper's outstanding achievement - Agnew

Cook passed Gooch's record when he reached 32

It is a massive achievement for Alastair Cook to become England's all-time leading Test run scorer.

Of the 667 people to have played for England, none have more runs than Cook, who passed Graham Gooch's record of 8,900. It's quite brilliant.

On day one of this Headingley Test against New Zealand, I talked about the ups and downs of James Anderson's 400 Test wickets, with the achievement being made all the greater because of past struggles.

Cook, like Anderson, has been at rock bottom. Between 2008 and 2009, Cook went 29 innings without a Test hundred, a slump that was not fully arrested until a century in the final Test of the 2010 summer against Pakistan secured his place on the Ashes tour.

More recently, against the backdrop of a struggling England team and the Kevin Pietersen saga, the opener went 35 innings without a ton, a run ended in the West Indies.

Both barren spells were characterised by the same technical issues - not getting fully forward into the ball, slightly falling over.

But, if you are to have a long career, you will experience problems and you usually return to the same person or coach to help solve those problems. For much of Cook's career, that mentor has been Gooch, though we do not know how much Gooch has had to do with this latest return to form.

Still, it is ironic that Cook has beaten the record of his long-time mentor, and it is probably true that he is England's bravest and most determined cricketer since Gooch.

Who knows what might have happened to Cook had he not come out of that early poor trot. If he hadn't, he might have missed out on that 2010-11 Ashes tour, which is where I think he was at his best for England.

The left-hander scored 766 runs, including three hundreds and a match-saving double century in the first Test at Brisbane. For me, that is his best innings for England, not least because the Ashes may not have been won without it.

It is difficult to compare eras, to fully evaluate where Cook ranks in comparison to England batsmen of the past. The familiar argument is that there is more Test cricket nowadays, often against much weaker opposition.

I would have loved to have seen Cook bat at the other end to Gooch, to see how he would have coped with the ferocious pace attacks that his fellow Essex player came up against in the 1980s.

However, the suspicion is that if you can bat beautifully in one era, there is no reason for you not to be able to do it in another. Cook would probably have done just fine.

It was clear that England had a very special talent on their hands when he announced his arrival with a debut hundred in India in 2006.

Cook was a fresh-faced 21-year-old when he hit a century on debut in Nagpur in 2006

Cook had flown from the West Indies, arriving into a fairly shambolic tour where the captain and vice-captain had gone home, with Andrew Flintoff thrust in as skipper.

In almost unbearable heat in Nagpur, Cook made 60 and 104 not out. We knew he would be good, but he's been much more than good.

Will his legacy be affected by how he is viewed as a captain? In fairness to Cook, he's done some very good things as captain, not least winning in India when he first took the job.

Some will choose to remember the 5-0 defeat in Australia and the Pietersen row, in which Cook has been embroiled.

But you only had to be at Headingley to see the affection that England supporters have for Cook. The applause when he passed Gooch's record with a drive for four off Tim Southee was loud, warm and sustained.

There have been some horrible and unkind things written about him in the press, painting a picture of a man who is self-obsessed.

That could not be further from the truth, for you could not wish to meet a more down-to-earth individual. Indeed, that is one of his great strengths.

When he is not playing, he returns to his family, his friends and his mates, totally getting away from the game.

I wouldn't say that I know him well, but I have certainly worked with him a lot. There was probably a time last summer when Cook was sick of me asking difficult questions.

Cook's landmark was warmly applauded at Headingley

Yet he is always friendly, unfailingly polite and with the impression that he is pleased to see you. That character is also obviously one that he has around his team-mates, who have immense respect for him.

When he retires from playing, you can imagine him walking away from cricket completely. I suspect the only place I will see him is at Melton market, buying sheep.

That is still a long way off, though. He is only 30 and could play for four or five more years, notching another 40 or 50 Test matches and probably passing 11,000 runs.

His immediate concern is Australia and he will begin the task of winning the Ashes back with the record out of the way, some good form under his belt and with a team that is creating some positive headlines for English cricket.

During the first Test I spoke about how this summer could be his last as captain, but I don't think it would be a good thing to push Joe Root into the firing line yet.

The best for the England team would be for Cook to remain as captain until at least the tour of South Africa at Christmas and perhaps into next summer too.

Jonathan Agnew was speaking to BBC Sport's Stephan Shemilt.

Listen to Geoffrey Boycott and Jonathan Agnew review the day's play on the Test Match Special podcast.

Get wicket alerts, end-of-innings scores and results sent to your mobile from the BBC Sport app.

Cook eventually fell for 75 when he was trapped lbw by spinner Mark Craig