Her statement followed the publication of an eyewitness report that her top Brexit negotiator had said earlier this week that the EU would "in the end ... probably just give" Britain an extension to the two-year withdrawal deadline if requested.
Olly Robbins is a senior U.K. civil servant who has helped oversee Britain's negotiations with the European Commission for much of that period. After a dinner meeting on Monday between his ministerial counterpart, the U.K. Brexit Secretary Stephen Barclay, and the EU's own chief negotiator, Michel Barnier, an ITV News correspondent overheard Robbins tell two colleagues in a hotel bar that British lawmakers should be made to believe that, "if they don't vote for the deal then the extension is a long one."
Political analysts say that kind of binary option might pressurize pro-Brexit members of Theresa May's Conservative Party to support her divorce deal with Europe — despite their continued concerns about a key provision of it — to avoid backlash from constituents who could see any delay to Brexit as a slippery slope to its reversal.
And though May dismissed the account as "bar chatter," some of her chief political antagonists have seized on Robbins' reported comments. The Scottish National Party's Westminster leader, Ian Blackford, said the prime minister's plan had been "rumbled by your own loose-lipped senior Brexit advisor," and insisted she should publicly prolong the negotiating period to avoid a no-deal scenario that was sought by what he termed "extremists" in her own party.
"The prime minister must stop playing fast and loose," said Blackford. "Businesses are begging for certainty, the economy is already suffering."
Days before the start of London Fashion week, that call for clarity was echoed by Caroline Rush, the chief executive of the British Fashion Council (BFC).
"We want some kind of idea, of course as every industry does, what the deal's going to look like, and going to a no-deal scenario will of course cause challenges for many businesses," she told CNBC Wednesday morning.
The BFC says the U.K. fashion industry is worth £32 billion ($41 billion) to the British economy, more than the car manufacturing sector that has frequently dominated Brexit-related media coverage in recent months.
On Tuesday, May had once again asked MPs to be patient as she seeks to find a breakthrough compromise from her European counterparts, with a little over six weeks until her self-imposed deadline.
Last month a parliamentary majority demanded she work to replace a key element of her proposed withdrawal deal with the trading bloc, an insurance policy known as the Irish backstop. European officials have spent the past two weeks since then reiterating that no such replacement is possible, or acceptable.
Labour opposition leader Jeremy Corbyn has consequently accused the prime minister of "running down the clock" until the late March deadline, with what he termed her "pretense" of continuing to work on cross-party initiatives to break the deadlock.
He said May's latest bid for more time was intended to "blackmail" lawmakers into voting for her current withdrawal agreement with Brussels, at the last possible moment, simply to avoid an economically and logistically messy no-deal departure.
But Conservative MP Greg Hands said the British premier had been "right" to ask for more time. He told CNBC Wednesday that: "If we get some movement from Brussels, some spirit of compromise coming out of Brussels, rather than this hardline attitude, then I think that we could be in business."