BT Parental Controls are too strict
Sites are categorised based on the main purpose of the website: not individual pages.
If a site is blocked that you think shouldn’t be, you can report this to us. Send details of the site by email to firstname.lastname@example.org.
Note that you can add sites to the "blocked/allowed" sites managed by the account holder by logging into My BT online and clicking Manage in the BT Parental Controls area.