The member for North Tyneside shares Mr Blair's relaxed, confident manner and finely tuned antennae for the political sensibilities and allergies of others . Rare is the New Labour revisionist, or indeed the thinking Conservative, who leaves a convivial lunch with Byers without feeling that of all the sparkling New Labour breed, this is the man who best understands their concerns. Unlike the luckless Frank Field, he has gained widespread approval outside his party without alienating those within it.
In his first Government job as Minister for School Standards, Byers proved equally adept at dealing with the less than ardently Blairite teaching unions and worked alongside the far more traditional David Blunkett without noticeable strain. If relations with the NAS/ UWT's rebarbative Nigel de Gruchy were at times tart, he formed a relationship of mutual regard, if rarely total agreement, with the NUT's Doug McAvoy.
But Byers is sceptical of the ingrained ways of the public sector. It is he who ensured that the new professional teaching body, the General Teaching Council, conceived to enforce high professional standards, featured only a handful of union representatives and a lot of practising teachers.
Like the Prime Minister, he has the knack of speaking with many voices, without ever quite contradicting himself. Since the election, he has thumped home the key message Blair wanted to disseminate about the need for improvement in the performance of state schools. But in front of union audiences, he would invariably begin by saying that teachers were doing "a very tough job in difficult circumstances" and (pointing to the reporters in the front row) that he would send a bottle of champagne to any journalist who reported this comment, rather than conveying a less flattering picture of the embattled profession .
"The delegates were always softened by this," an education correspondent recalls. "Afterwards though, Stephen would brief that the Government intended to be tough on this, or wouldn't stand for that - so he always got the headlines he wanted in the end, while appearing to be shaking his head at the press for being so hard on teachers."
Before his official promotion, self-promotion came naturally to him. As employment spokesman in opposition - a post once held by Mr Blair - he would send out a newsletter boldly headed "The News from Stephen Byers". Irritated by newspapers reproducing a dated picture of him with unkempt hair and a moustache(a very Old Labour accoutrement), he despatched to newsdesks, shortly after the election, one photograph of himself smiling and another looking serious, to ensure that a suitable illustration matched the mood of any story which involved him.
The son of an RAF technician, Byers attended Chester City Grammar School. Seized by the mood of 1968 and irked by the constraints of a very formal grammar school, he moved to the local College of Further Education for his A-levels before taking a law degree at Liverpool Polytechnic and becoming a law lecturer at Newcastle Polytechnic, during which time he joined the Labour Party.
Throughout the 1980s, Byers was on North Tyneside council, where he was one of the young bloods intent on ditching the inbred, Our Friends in the North right-wingers, while out-manoeuvring a Militant challenge. "That put steel in my back-bone," he recalls. He was elected to Parliament for Wallsend in 1992, moving to the North Tyneside seat and the more elegant base of Fenham, a prosperous suburb of Newcastle, in the 1997 boundary change.
Even in Labour, it is unusual for products of this modest educational background to prosper as fast as he has done. "He is a true meritocrat," says a colleague, "He doesn't need the security of an Oxbridge degree to sound sure of himself." But he had odd moments of vulnerability. Asked last year on a radio show to multiply eight by seven, he came up with 54 instead of 56 and appeared flummoxed when teased about it. He has since learned the politician's trick of telling the story against himself, rather than letting his opponents exploit it.
His bond with the Prime Minister was forged in the North-east where the County Durham-based Blair and Hartlepool-based Peter Mandelson were seeking out allies for party modernisation in the neighbouring constituencies. Mr Byers and the Darlington MP Alan Milburn soon emerged as his favourites and each were given key junior posts and tipped for rapid promotion. For most of the last year "Byers and Milburn" have tripped off the tongue as the most promising duo, as if joined at the hip. But this time, it is Mr Byers who has edged ahead. Mr Milburn must wait his turn.
Byers' ultra-Blairite credentials were established at the 1996 TUC Conference when, over dinner with lobby correspondents, he floated the idea that the Labour Party might cut its links with the trade unions . It has always seemed more than likely that this was a test-balloon for a controversial idea launched by the leadership and entrusted to Byers to float. The union response was furious. But it would not be uncharacteristic of him to have heightened the impact of the suggestion beyond Blair's intentions. "Stephen does like to be at the centre of storms," says a colleague. If he did exceed his brief, it was treated with indulgence.
In his new role, he will have to practise discretion. The Treasury has its own ways and dislikes attention-seekers. He has also been appointed to the Chief Secretary's post as a key player in the balance of power between Tony Blair and Gordon Brown, and will have to expend some of his boundless energy sweetening those members of the Chancellor's entourage who regard him as a spy from the Blairite camp.
The substance of his job will be to deal with the detail of the Comprehensive Spending Review - a role which will sharpen up that hit-and-miss mental arithmetic. Now that spending targets have been set, he will monitor the expenditure plans of the various departments to ensure that they fulfil Brown's promised value for money.
With the Financial Services and Markets Bill heralding the arrival of a single regulator of the City's wheeling and dealing, Byers has been entrusted with the task of reassuring New Labour's hard-won contacts in the Square Mile. Together with Alistair Darling, his predecessor in the job and now in charge at Social Security, Byers is intended to be a key figure in pushing forward welfare reform, helping Darling draft concrete proposals for changes to the pension system and housing benefit. He knows that the leadership is sensitive to accusations that it is letting reform of the welfare state slide and that the time has come to channel some of the earlier rhetoric into action.
So far, he has avoided the Blairites' worst tendency of taking themselves too seriously, and keeps a wide circle of friends from outside politics. He once confessed to them that, after a vinous lunch, and aware of the diktat that New Labourites should always look their best, he had bought a "truly awful" expensive suit he didn't need. Well-liked in his constituency, he filled his house with local party activists to watch Newcastle United lose the FA cup. Most weekends are spent in the constituency with his long-term partner Jan, a solicitor. Both are keen gardeners and walkers.
It is the combination of fierce and focused ambition and ease with himself which has made him such a shooting star. If the Prime Minister has a particular soft-spot for him, it is the benevolence those who have made it feel towards those they have cast in their image.