Faull, who heads the European Commission's Brexit team, told the European Parliament's constitutional affairs committee on Thursday that intense discussions both between and within the EU institutions and national governments are underway on how best to respond to David Cameron's renegotiation demands.
"I think expectations have been raised that an agreement [on the British demands] is possible in February. Our hope in the European Commission is that this [February Council summit of EU leaders] will be a decisive one.
Faull told deputies that the commission's role in the discussions was primarily one of guidance and ensuring that any deal does not threaten the EU's fundamental four freedoms, including the free movement of people.
"The Commission's position is that we want to be helpful…to play a role in crafting solutions to the problems that have been raised and to ensure that the integrity of the EU's legal system is maintained."
In what former MEP and EU constitutional expert, Andrew Duff called "masterful non-answers to mainly patsy questions from MEPs", Faull said that the British demands and the threat of a UK exit "were not trivial issues" and had provoked, "strong opinions".
MEPs questioned him on whether he thought that the crucial British demand to exempt EU migrant workers in the UK from accessing in-work welfare benefits until they have been in the country for four years could be reconciled.
Faull admitted he couldn’t yet say, but hinted that the "EU's fundamental freedoms were, "fundamental, but not unconditional."
The question, he said, is whether the EU's constitutional framework, "contained enough flexibility" to deliver a solution that would satisfy all players.
When pressed on what a possible agreement on the in-works benefits could look like, Faull alluded to the architectural maxim that "Form would follow content" and that, "nothing is agreed until everything is agreed".
"Sometime in early February papers will have to be issued [ahead of the council summit on 18-19] and then the issue will become a public debate across the EU. [But] "I think the political will to resolve this issue is pretty strong."