“Significant progress has been made…including (in) discussions on the text of the treaty and its implementation,” he told reporters at a press conference in Madrid with Spanish Foreign Minister José Manuel Albares.

Although Brexit threw Gibraltar’s future into question, raising fears it would create a new “hard border” with the EU, negotiators reached a landmark framework deal for it to benefit from the rules of the Schengen zone just hours before Britain’s departure from the bloc on January 1st, 2021.

Negotiators from Britain, Spain and the EU have been meeting to thrash out the details of the agreement in order to ensure freedom of movement along the border of the British enclave at Spain’s southern tip.

“We were discussing how this could unleash an unprecedented level of economic growth for all those in the region,” the British minister said after several hours of talks with Albares, which were to carry on into the evening.

“We are fully invested in agreeing a deal as soon as possible,” Cleverly added, expressing confidence it was possible “to agree a treaty that protects our respective positions on sovereignty”.

Joint use of the airport

Gibraltar’s economy provides a lifeline for some 15,000 people who cross in and out to work every day, most of whom are Spanish and live in the impoverished neighbouring city of La Linea.

“We have both agreed to move forward as quickly as possible to reach a definitive agreement,” said Albares.

On November 25th, he laid out details of a proposal presented to Britain under which the border fence between Spain and Gibraltar would be removed to ease freedom of movement and on Wednesday he said it would also involve “the joint use of the (enclave’s) airport”.

At his own press conference shortly afterwards, Gibraltar’s Chief Minister Fabian Picardo, who joined the ministerial talks by video link, said it was “a very positive meeting”.

But he said “areas of disagreement nonetheless still remain”, noting Gibraltar had already “rejected the concept of joint use of the airport”.

With a land area of just 6.8 square kilometres (2.6 square miles), Gibraltar is entirely dependent on imports to supply its 34,000 residents and the deal was crucial to avoid slowing cross-border goods trade with new customs procedures.

Although Spain ceded Gibraltar to Britain in 1713, Madrid has long wanted it back in a thorny dispute that has for decades involved pressure on the frontier.

READ MORE: Why is a post-Brexit Gibraltar deal taking so long?