Robinson (left) - fine sight in full flow.

By Frank Malley, PA Chief Sports Writer

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The twinkling feet of Jason Robinson tap-dancing through the opposition is one of the finest sights in rugby.

It is England's most potent weapon as they prepare for a momentous Grand Slam decider against Ireland at Lansdowne Road next Sunday.

It is almost certainly the special factor which could determine England's fate in the World Cup later this year.

Like the purest tone of a Stradivarius, Robinson's quality is undeniable. The problem for England coach Clive Woodward is in choosing the position from which it is best to unleash his talents.

Is it full-back, which allows Robinson time and space to select his most mesmerising line of running but from where Josh Lewsey has played with impressive enterprise and penetration in the last two internationals?

Is it the wing from where Robinson forged his reputation as a bewildering runner during nine years in rugby league in which he won very honour the sport had to offer?

Or is it outside centre?

On the evidence of England's 40-9 victory against Scotland in the Calcutta Cup yesterday there is a powerful case for Robinson's game-breaking skills being housed in the more central role.

For the best part of an hour out wide Robinson was restless and fitful, hungrily seeking the ball but struggling to make an impact as anything other than a peripheral figure.

He even spent 10 minutes sitting on the bench in the sin bin after a ludicrously harsh decision by Irish referee Alan Lewis who deemed his harmless, marginally late tackle on Chris Paterson to be worth the same punishment as two blatant and reckless mid-air challenges by Scotland's Andrew Mower and Simon Taylor.

But once Robinson was re-directed to outside centre in place of the injured Mike Tindall, with Dan Luger going to right wing, a light was switched on in the Robinson repertoire.

Two tries followed - one a jinking 50-metres solo thrust which alone was worth the admission fee.

It had the crowd on their feet, Woodward in raptures over a "fantastic" player - but left Robinson modestly fending off the plaudits.

"When you get your opportunities you just have to take them," said Robinson.

"The first half I was sniffing here, there and everywhere - but it just didn't happen.

"I've played outside centre a few times for Sale. I also love playing full-back. The main thing is I just want to get the ball in my hands. The more times you do that the more chance you have to do something."

England assistant coach Phil Larder put Robinson's work in sharper focus.

"He is the most dangerous and exciting runner in the game," said Larder.

"I am just pleased we don't have to work out how to stop him."

That is Ireland's job next Sunday - although England will have their own work cut out dealing with the championship's other prolific game-breaker, Irish centre Brian O'Driscoll.

"He is a real threat," admitted Robinson.

"He's playing very well and is a player we'll have to keep an eye on. He can produce something out of nothing, and we must close him down.

"I don't think we'll need too much motivation. Our thoughts will be on how we performed last time. We want to make up for that and finish off the Six Nations on a positive note."

The memory of England's last defeat at Lansdowne Road in October 2001, which robbed Woodward of yet another Grand Slam opportunity, somewhat intruded on their celebrations yesterday - especially for the likes of scrum-half Matt Dawson, who captained the team 18 months ago but was forced to go off injured.

"That was a bitter pill to swallow, a real low moment for me," said Dawson.

"We were outplayed."

The new Dawson doesn't dwell on anything, though.

"England have progressed as this championship has gone on," he said.

"But in Ireland we have got to try to be a bit more relaxed. We have been too tense and emotional before. There are star players on both sides, and any one of them can win matches."

None is more precious to England's cause, however, than Robinson - a man destined to be the centre of attention wherever he plays.