Britain’s Brexit minister David Frost resigned on Saturday “with immediate effect,” dealing another blow to Prime Minister Boris Johnson’s crisis-ridden government. The resignation came after The Sunday Times reported that Lord Frost had handed his resignation in earlier this month, but agreed to stay until January after Johnson told him the government could not cope with a high-profile departure at the moment. In a letter to the prime minister released on Saturday evening, Frost said he was “disappointed” that his planned departure had become public and “in the circumstances I think it is right for me to write to step down with immediate effect.” Frost said that during Johnson’s premiership, “we have restored the UK’s freedom and independence as a country and begun the process of building a new relationship with the EU.” But he said “that will be a long-term task” and that was why it was agreed he …