But in an ironic twist, that argument soon turned into an embarrassment, as markets reacted to May's determination to pursue Brexit. The British sterling lost so much value against the euro that Britain dropped to the sixth spot in international rankings, falling behind France. After May's speech, the sterling had fallen to a 31-year low against the dollar.
The Financial Times calculation is based on market exchange rates, which are considered imperfect by some economists. However, the exchange rate-based drop in economic size is only one of many indications that Britain's economy could suffer under the fallout from Brexit.
Most international institutions, including the International Monetary Fund, have repeatedly emphasized the economic risks of the referendum. More recently, some banks and international companies have publicly said they were considering moving their headquarters to other E.U. nations.
May has tried to steer the public debate away from the Brexit negotiations and toward other, more domestic issues. However, some statements by members of her cabinet have achieved the opposite.
Associations representing British companies reacted with anger and confusion to an announcement Wednesday by Home Secretary Amber Rudd, who had proposed to force companies to publish the number of foreign workers they employed.
Relying on a sense of dark British humor, many commentators on social media later wondered whether mandatory armbands for foreigners might be next.