Could a U.S.-Britain trade deal help take the sting out of Brexit? U.S. President Donald Trump certainly seems to think so, telling The Sunday Times that, “We have tremendous potential to make up more than the difference,” and, after arriving in London on Monday, tweeting: “Big Trade Deal is possible once U.K. gets rid of the shackles [of the EU].”
But speaking at the Fortune Most Powerful Women International Summit in London on Tuesday morning, Baroness Rona Fairhead CBE, the U.K.’s former minister of state for Trade and Export Promotion, did not appear convinced by Trump’s pronouncements.
“[The EU countries] still remain our closest partners in terms of location—and they still represent about 50% of our trade,” said Fairhead. She cited a Parliamentary study that found that Brexit and the associated cost of disrupted trade with the EU would reduce the U.K.’s GDP by between 2% and 8% over a 15 year period. Any other deal—including with the U.S.—would result in a less than 1% gain over the same time period, said Fairhead.
That’s not to downplay the importance of a strong trade deal with U.S., said Fairhead. Specifically, she pointed to the value of an agreement based on services, which she considers an somewhat overlooked area. “On the services side, there is more potential there. We’re both big services nations.”
More must-read stories from Fortune:
—Why Alibaba’s Hong Kong IPO may signal a Chinese retreat from Wall Street
—Italy is threatening to repeat the Greek debt crisis—but with higher stakes
—China is creating a “Greater Bay Area” to rival Silicon Valley
—The Indian elections were influenced by immigrants in the U.S.
—Listen to our new audio briefing, Fortune 500 Daily
Keep up with the world’s most powerful women with Fortune‘s Broadsheet newsletter.