'Total destabilisation' of the economy? A strong warning on the risks of EU referendum...and some support

Is it "scaremongering"? Or would it be a "total destabilisation"?

Our position in the European Union has always stirred up strong feelings but as the time (finally) nears for the Prime Minister's speech on the subject, I've been speaking to the leaders of two of the biggest companies in the UK.

With the economy so fragile, their views are certainly ones that politicians are under pressure to consider.

Sir Roger Carr, the chairman of British Gas owners Centrica, one of the biggest companies in the country, believes the debate is already damaging.

Centrica employs more than 30,000 staff and Sir Roger is also the chair of the powerful CBI.

He warned in strong words against walking further down the road to a referendum on Europe.

He said to me a wholesale referendum could mean a "total destabilisation" of the economy and threatens UK jobs.

Sir Roger said that if the PM promises an in/out referendum, it is an "anti-growth position". The debate has already given investors a reason to "think twice" about spending money here at a time when the economy needs it so much, he said.

"For inward investors who look to Britain to be the bridge into Europe, it is a reason to think twice, and I think none of that is good for the British economy.

"It is about jobs, it is about investment, it's about confidence, confidence for those who look to Britain to be a place to invest as outsiders, confidence from those who run businesses in Britain.

"Anything that can undermine the potential for growth - and I think total destabilisation by a stark in/out referendum decision could do that - is an anti-growth position."

Sir Roger went on to tell me: "If we indicate we are seriously considering leaving Europe, we will lose allies within Europe, that would be damaging.

"That would be damaging to the growth prospects of the country and the employment levels of the country, and we would no longer be seen as a safe haven.

"That's what's at risk by putting Europe at risk."

In the Prime Minister's corner, arguing for re-negotiation, is the boss of the clothing chain Next.

He employs over 50,000 people. Lord Wolfson, himself a Conservative peer, has continually defied the grim trends in retailing to build his business bigger and bigger and bigger.

But although he does not want the UK to leave the European Union, he believes it is vital to change our relationship, and right now.

What's more, he accuses those warning against, like Nick Clegg, who says there would be a "chilling effect on jobs", of scaremongering.

He told me he thought the Deputy PM was talking "absolute nonsense - it is scare tactics from someone who has never run a business."

"We have heard these scare stories before," he said, "the same people made that threat when we didn't join the Euro 10 years is the same people making the same warnings about a different subject.

"He was wrong then, he's wrong now."

Far from there being danger in having this debate, he said, "there is absolutely nothing wrong, or dangerous about Britain sticking up for her interest."

Those warning against, he said, are "listening to the counsel of their own fears."

Lord Wolfson does not advocate exit, but a renegotiation of powers. But he acknowledged there is a risk to the Conservatives from UKIP, and a "risk of Britain being in or out is there anyway, you only have to look at the strength of UKIP to realise this is a live issue.

"Having this debate is vital to us staying in," he concludes.

The business world is large and complex, and as I've written before there is no one single view.

In general, the bigger the business, the more they trade with the rest of the world, the more concern they have about the path the Prime Minister may set out.

Yet even for these two whose views contrast so much, they do agree on one thing - when he finally gets up to give this critical speech, the Prime Minister will be walking a tightrope.

With the economy so sensitive it's not just his party, the public, or the coalition that David Cameron has to have in mind.