Sherlock viewers have met the detective’s parents twice before in the series, once in season three opener The Empty Hearse when they visited his Baker Street flat for tea and again when the Holmes family gathered together for a cosy Christmas in the final episode of the run, His Last Vow. Wanda Ventham, 81, and Timothy Carlton , 77, play Mr and Mrs Holmes, and they made another appearance in Sunday night’s series four finale, The Final Problem.