She said Theresa May had her "full support" but in a pointed message about the kind of Brexit deal she wants, Ms Jenkyns said: "We want to see a new relationship with Europe, with a new model not enjoyed by other countries - nothing that leaves us half-in, half-out".
The official also said that the United Kingdom will start having to take responsibility for its decision and accept that Brexit will mean a looser relationship with the EU.
The real fun and games start at paragraph 14 of the document, with a shaky finger pointed at the 8 December 2017 Joint Report (PDF) issued by the United Kingdom and European Union negotiators, which states that the United Kingdom can continue to take part in European Union programmes that were financed between 2014 and 2020 until their closure.
The official said Britain had promised a new proposal on the Irish issue and Brussels hoped to have them early next month.
Last December, the European Union and United Kingdom agreed a draft deal on key divorce issues, including Britain's financial settlement.
May suggested making the backstop time-limited.
"We need to have the recognition that the backstop has to be Northern Ireland-specific", the official said.
Any future relationship would rely on trust, the official said, but Britain could not expect the same treatment as member states subject to stricter European Union oversight.
Image Jacob Rees Mogg has warned the PM to show 'backbone'
The official said the United Kingdom has promised new ideas within the next two weeks, but sounded concerned about possible progress.
The blunt warning comes as the withdrawal agreement needs to legally finalised by October for it to be ratified by the United Kingdom and the European Parliament before Brexit-day next March.
Other issues of separation also presented hard obstacles during the three days of talks.
DExEU presented its plans on Wednesday for a future science, research and innovation partnership between the United Kingdom and EU, which included a promise to "respect the remit" of the European Court of Justice (ECJ) when the United Kingdom participates in EU programmes.
The UK also wants to continue participating in the EU's criminal extradition system and the high-security parts of the Galileo satellite programme.
The official emphasised that the the EU's cooperation is based on common rules with a common legal oversight and the United Kingdom can not expect the same treatment without agreeing to the legal remedies.
Earlier this week, Mr Carney said Brexit has knocked real household incomes by around £900, and lowered growth by "up to 2%" against what the Bank of England had expected in 2016 if the United Kingdom had voted to remain in the EU.
- Deutsche Bank said set to embark on big equities retreat following review
- GDPR Arrival Sees Certain US Websites Blocked
- The 2018 hurricane season expected to be near or above-normal
- The Book on Sports Betting: The House Holds the Cards
- NY judge orders son, 30, to leave parents' home
- Ex-DNI James Clapper Calls Trump's FBI Spy Claims 'Distorted'
- Samsung ordered to pay $539 million in damages to Apple
- Facebook rolls out new political ad disclosures
- Latest Ontario Election Polls Show NDP Gaining Ground, Tories Stalling
- Suspect in custody after shooting at in middle school