David Cameron's hard won EU renegotiation deal will make no difference either way for British business leaders, according to a snap poll from the Institute of Directors (IoD).
The survey, of 672 IoD members between 20 and 21 February, also found that just 10% of business chiefs thought Cameron's settlement was bad, while 34% of respondents said it was good.
The research revealed that only 54% of businesses had discussed the historic ballot at a senior management or boardroom level, with 44% of leaders saying they had not, and 2% revealing they did not know.
Simon Walker, the director general of the IoD, urged UK-based companies to think carefully about how the forthcoming EU referendum would affect them. "Businesses will weigh up the reforms when considering the pros and cons of EU membership as they decide how to vote at the referendum," he said.
"The issue is of course much larger than this agreement. Our members have concerns about the way the EU operates in some areas. But this is balanced against the ability to trade easily across the single market. Their operations are deeply entwined with the EU – more than three-quarters have commercial links with other member states.
"It is worrying that four in 10 firms have not discussed the referendum in the boardroom. Now that a date has been set, all firms should consider what the potential outcomes would mean for them."
The research comes after the Mayor of London Boris Johnson dramatically announced his support for a Brexit on 21 February.
"It is not clear why the [European] Commission should be best placed to know the needs of UK business and industry, rather than the myriad officials at UK Trade & Investment or the Department for Business, Innovation and Skills," the top Tory wrote in The Daily Telegraph.
"If the 'leave' side wins, it will indeed be necessary to negotiate a large number of trade deals at great speed. But why should that be impossible? We have become so used to Nanny in Brussels that we have become infantilised, incapable of imagining an independent future.
"We used to run the biggest empire the world has ever seen, and with a much smaller domestic population and a relatively tiny Civil Service. Are we really unable to do trade deals? We will have at least two years in which the existing treaties will be in force."
Business Secretary Sajid Javid has unexpectedly thrown his support behind a 'remain' vote. "The fallout from a 'leave' vote this summer would only add to economic turbulence that is, quite possibly, about to engulf the world," he warned in the Mail on Sunday.
"Some have even warned that Brexit could precipitate the total collapse of the EU, and while I know that many might welcome such a prospect, the shockwaves could prove catastrophic in the current climate."
The latest opinion poll from Survation, of more than 1,000 people between 13 and 20 February, gave 'remain' a 15 points lead over 'leave' (48% versus 33%), with 19% of respondents undecided.