A farthing, a half penny, a penny and a two penny coin were all made from copper but to 'earn a copper' usually refers to receiving a penny. One of the loafers outside Briony Lodge rushed forward to open the carriage door for Irene Adler in the hope of earning a copper. (A Scandal in Bohemia) 

 

That was to be the prize for the Baker Street Irregular who found the 'Aurora'. (The Sign of Four)

 

Godfrey Norton paid his cabbie half a guinea to get him from Briony Lodge to St Monica's Church via Regent Street in twenty minutes. (A Scandal in Bohemia)

 

'Holmes took a half-sovereign from his pocket and played with it pensively'. He did this while he was waiting to hear John Rance's report on what happened at 3 Lauriston Gardens. (A Study in Scarlet)

Watson paid Mr Sherman a half-sovereign for the use of Toby. (The Sign of Four) 

Irene Adler gave her driver half a sovereign to get her to St Monica's Church in twenty minutes. (A Scandal in Bohemia)

Holmes paid his cabbie half a sovereign to get him to the Church of St Monica's in twenty minutes. (A Scandal in Bohemia)

 

Loose Money
No purse was found on Enoch J. Drebber but he was carrying 'seven pounds thirteen'. (A Study in Scarlet) 

 

Enoch J Drebber and Joseph Stangerson paid Madame Charpentier a pound a day each for boarding at

her house. (A Study in Scarlet)

 

Joseph Stangerson had Enoch Drebber's purse on him when his body was found in Halliday's Private Hotel. It contained £80. (A Study in Scarlet)

 

The King of Bohemia gave Holmes £700 in notes and £300 in gold towards expenses for the recovery of the photograph of Irene Adler and himself. (A Scandal in Bohemia)

 

Holmes gave each of the Baker Street Irregulars a shilling to keep searching. (A Study in Scarlet)

Holmes handed each of the Baker Street Irregulars a shilling as a day's pay in advance, they were looking for the 'Aurora'. (The Sign of Four)

 

Irene Adler gave Holmes a sovereign for acting as witness at her wedding. Holmes pledged to wear it on his watch-chain. (A Scandal in Bohemia)

 

Wiggins and the Baker Street Irregulars rush into 221B Baker Street. Holmes produces some silver and then gives Wiggins details of the 'Aurora'. (The Sign of Four)

 

Holmes was given £300 in gold plus £700 in notes towards his expenses by the King of Bohemia. (A Scandal in Bohemia)

 

Holmes received this in payment of his work as a groom at Briony Lodge. (A Scandal in Bohemia) 

 

Jack Smith told Holmes that 'two shillings are better' when he was asked what he would like. (The Sign of Four)