The website Old Bailey Online gives details of cases from 1674 to 1913. Using the search facility with the officer’s surname it is possible to find cases where Metropolitan Police officers gave evidence at the Old Bailey. An example is given below for PC Walter Cursons where he gave evidence against Thomas Savage who was found guilty of grievous bodily harm and assault against three police officers. Savage was sentenced to one year with hard labour.
Although the Old Bailey now normally deals with major cases some of the earlier cases were actually quite trivial. If the man you are researching was a detective it is quite likely that he may have given evidence at the Old Bailey on several occasions.