Complex sentence: Miss Warrack was a woman of strong force of character, an admirable organiser, and never failed to leave the impress of her marked individuality on her pupils, who, in after life, were ready to recognise the potent influence which she exercised upon them.
Split into simpler sentences: Miss Warrack was a woman with strong force of character, an admirable organiser who never failed to leave the impress of her marked individuality on her pupils. In later life, her students were ready to recognise the potent influence which she exercised upon them.