LONDON (Reuters) - Prime Minister Boris Johnson’s top adviser Dominic Cummings will continue to work until mid-December, and another senior aide will serve as temporary chief of staff, Johnson’s office said on Friday. Cummings had earlier been pictured walking out of Johnson’s Downing Street office with a box in his arms, and several local outlets had reported he had quit his post with immediate effect. Director of Communications Lee Cain would also stay in post until mid December. “The Prime Minister has today asked Sir Edward Lister to take on the role of chief of staff for an interim period pending a permanent appointment to the post,” A Downing Street spokesman said.