Irene Adler's maid rushed across to the windows of Briony Lodge when Holmes motioned that he needed air. (A Scandal in Bohemia)

 

A short deep-chested man, he was the porter (gatekeeper) of Pondicherry Lodge. He was an old boxer who fought three rounds with Sherlock Holmes at Alison's Rooms on the night of his benefit. (The Sign of Four)

 

The milk boy was walking down the lane behind the Halliday's Private Hotel where he saw the murdered of Joseph Stangerson. (A Study in Scarlet)

 

The governess to the family of Mrs Cecil Forrester. 'A blonde young lady, small, dainty, well gloved and dressed in the most perfect taste', is how Watson describes Miss Morstan after the first time he sees her. She later explained that her father was dead and on the anniversary of his death, she receives a precious jewel. And so the exciting second stories of Sherlock Holmes begins. (The Sign of Four)

 

Captain Morstan was in an Indian Regiment. In 1878 he returned to England on twelve months leave. His daughter, Mary, travelled from Edinburgh to visit him at the Langham. He disappeared on the 3rd December 1878.

 

Harry Murcher

A police officer from Brixton, who's beat was around Holland Grove. He assisted PC John Rance during 'A Study in Scarlet'.