There are reports that EU leaders have been told to keep Sunday, November 25 free for a possible summit in Brussels to ratify the deal. That would enable Parliament to vote on it before Christmas.
Mrs May faced continued demands to publish the full legal advice on which her proposals for the backstop arrangement are based, with former Brexit Secretary David Davis suggesting she is reluctant to do so because she is yet to “pin down” key points.
Jeremy Hunt, the Foreign Secretary, said agreeing a deal within the next week would be “pushing it” but added that he was “confident” agreement would be reached by the end of the month.
There are fears, however, that EU negotiators will use the “ticking clock” as leverage to ensure that EU fishing fleets maintain their current levels of access to UK waters for as long as the UK remains in a customs union.
Mrs May has negotiated for a UK-wide backstop arrangement to avoid a hard border in Northern Ireland if no trade deal can be finalised by the end of the transition period in December 2020. The EU wanted a Northern Ireland-only backstop and is determined to extract a high price for allowing the whole of the UK to be included in the arrangement.
A UK-wide customs union deal would hand quota and tariff-free access to EU markets for the British fishing industry, which exports 75 per cent of its total catch to Europe.
In return for that market access, the EU has made clear that it will demand continued “status quo” access to UK waters for their trawlers, even though the UK will have departed from the Common Fisheries Policy. The French, Danish, Spanish and Portuguese governments are under particular pressure to deliver for their fleets.
One EU diplomat told The Telegraph: “It is paramount the UK gives assurances on the access of the European fleet to UK waters before the EU can agree to a UK wide backstop.”
Another diplomat from a major EU fishing power said: “There can be a customs union, but there must be rules to ensure that EU fisherman will be able to continue to fish in UK waters, otherwise there is no point in having a customs union.”
Britain currently keeps just 40 per cent of fish from its waters, with 60 per cent going to EU fishing fleets.
The Prime Minister said last month: “Once the EU rules no longer apply to the UK, we will be an independent coastal state, we will be making our own decisions, controlling access to our own waters and we will be seeking to gain a fairer share of quotas.”
Ramsay Jones, spokesman for the Scottish Fisherman’s Federation, said: “We would be against any guarantee of full continued access for the EU beyond December 2020. The Government must stand true to what it has said publicly.”
The Scottish Tories, who won a series of coastal seats from the SNP in last year’s general election, warned the long-awaited Conservative revival in Scotland would be destroyed if the party does not make good its promises to the country’s fishermen.
A senior Scottish Conservative source said: “The difficulty for the Prime Minister is she has to get the deal through Parliament and giving up this quota is not acceptable to Scottish MPs and the fishing industry.”
Ruth Davidson, the Scottish Tory leader, and Scottish Secretary David Mundell have privately made it clear to Mrs May that the Brexit deal must not tie the country in to future fishing quotas.
Sherryl Murray, the Tory MP for South East Cornwall, said: “Anything that would tie UK fishermen to the Common Fisheries Policy for a longer period than already confirmed would be totally unacceptable.
“Fishermen are already going to struggle with the current agreement during the transition period. I would not accept any deal that disadvantages our fishermen further.”
Current quotas give 84 percent of the cod in the English Channel to France and just 9 percent to Britain, according to UK industry sources; but totally excluding French boats out of UK waters cut French fishing revenues by 50 per cent and wages by 15 per cent.
In the Irish Sea, Northern Irish fisherman calculate they should get 43 per cent of the cod catch, but the CFP grants them only 30 per cent, according to Alan McCulla of the Anglo North Irish Fish Producers Organisation.
“All we want is justice,” said Mr McCulla. “No-one ever said EU boats should not fish in our waters, but Mrs May has promised to rebuild our communities after Brexit and she must not squander that opportunity.
“The Brexit dividend we expect is an end to the inequalities of the Common Fisheries Policy that has allowed trawlers from the Irish Republic to steal millions of pounds worth of fish from UK fishermen ever year.
“I’m confident in the prime minister and the negotiators. Do I really believe that with so few trump cards, Mrs May is going to surrender the one she has, and come out with nothing from this negotiation? No I don’t.”
A Government source said: “Michael Gove, David Mundell and the Prime Minister could not have been clearer, leaving the EU means taking back control of our waters. This includes in any, unlikely, backstop arrangement.”
At a conference in Finland Michel Barnier warned that the European Project faces destruction at the hands of populist forces in elections next year.
The EU’s chief Brexit negotiator said: “There is now a [Nigel] Farage in every country. The European project is fragile, it is under threat, it is perishable.”