1) Go to the BT calendar or event list you would like to sync.
2) Click the green rss feed icon
on the top right corner of the BT calendar/event list to open it.
3) Highlight the entire feed URL that is listed and right click to copy the URL.
4) Open your Google calendar. (Be sure you are signed in to Google)
5) On the bottom left side of your Google calendar under Other calendars, click the add button.
6) Choose add by URL.
7) Paste the previously copied BT feed URL into the open URL Box. Click Add Calendar.
You should now see the real time updated BT calendar on your Google Calendar.