If you are providing a direct quotation and it has come from a book then you should include the page number on which the quotation appears (but not the first page), i.e. Lucy Welsh, Layla Skinns and Andrew Sanders, Sanders & Young's Criminal Justice (5th edn, OUP 2021) 27. This tells the reader the details of the book according to OSCOLA’s prescribed format for citing books (s 3.2) and that the quote the writer has used comes from page 27.
Where you should provide the first page number is for cases and journal articles. Consult OSCOLA s 2.1 Cases and 3.3 Journal Articles for examples. In the following example the journal article reference is provided with its first page (656 - where the article starts) and the page number being (hypothetically) quoted from (660): De Than C and Elvin J, ‘Private Prosecution: A Useful Constitutional Safeguard or Potentially Dangerous Historical Anomaly?’ [2019] Criminal Law Review 656, 660.
Lastly, while you retain the first page of journal articles or case reports in the citations in the bibliography at the end of your work, you do not have to include any page numbers used for quotations from books or journal articles. For example, the above De Than citation in the bibliography would be De Than C and Elvin J, ‘Private Prosecution: A Useful Constitutional Safeguard or Potentially Dangerous Historical Anomaly?’ [2019] Criminal Law Review 656. The 660 is unnecessary here.
OSCOLA guide: oscola_4th_edn_hart_2012.pdf (ox.ac.uk)
