Boris Johnson was livid, and so was Dominic Cummings. After a series of rows that boiled down to who was really running Britain, the prime minister threw his most powerful adviser out of Downing Street on Friday.

With talks on a trade deal with the European Union on the line and the death toll from the coronavirus mounting, the resignation of Cummings marks a seismic rupture in Johnson’s inner circle at a critical time for the country.

Ministers, officials and members of parliament, who spoke privately to give their candid views, regard losing the maverick Cummings as a cause for celebration. Johnson himself knows he must reset relations with his Conservative Party and relaunch his mission to reform the U.K.