England's ever-lengthening list of questions remain

England’s laboured 25-13 victory over Scotland made them favourites to win their first Six Nations title.

Scotland wing Doug Fife (C) dives to attempt to tackle England full back Mike Brown (R) during the Six Nations international rugby union match between England and Scotland at Twickenham Stadium, south west of London on 14 March, 2015. England won the game 25 - 13. Picture: AFP

LONDON - England's laboured 25-13 victory over Scotland made them favourites to win their first Six Nations title since 2011 but it was a worrying reminder that they lack the ruthlessness to trouble rugby's big guns with the World Cup looming.

Saturday's victory was enough to see England regain top spot in the table courtesy of a plus four points difference over Ireland whose Grand Slam aspirations were dashed by a 23-16 loss to Wales but there remains an ever-lengthening list of unanswered questions for Stuart Lancaster's team.

Where is their ruthless streak? What is their best 15? Do they have the temperament to consistently challenge the best sides? Why the apparent complacency against perceived inferior teams? The list goes on.

Before the game England's 2003 World Cup-winning coach Clive Woodward said Scotland, who had conceded an average of 36 points per game in their previous seven visits to Twickenham, were so bad their rivalry had become "a myth".

Scotland briefly troubled England and led 13-10 early in the second half but eventually succumbed to defeat despite a dogged performance.

While victory against France next week is almost given having won four of their previous five Twickenham encounters against Les Bleus England's campaign is clouded by questions that should not be present in a side revving up for a World Cup assault in six months' time.

"We know we'll need to be more clinical if we are to get the job done against France," head coach Lancaster told the BBC.

"We are (playing) the last game next week so we will know what we need to do in terms of the championship. But you've got to win the game first and that's a big challenge against this French team."

There was nothing in England's performance against a wounded and under-resourced Scotland side that would have worried the likes of New Zealand, South Africa, Australia, Ireland or Wales.

England carved out 11 clean breaks, beat 26 Scottish defenders but crucially and inexplicably scored a meager three tries.

Provided with the same chances, other World Cup title contenders would have put a Scotland side more than likely consigned to the wooden spoon after four successive defeats to the sword.

Woodward, England's head coach from 1997 to 2004, said in The Mail on Sunday: "England have to recapture the coolness under pressure and ruthless streak. That is what wins you big rugby matches."