It provides slightly modified versions of Mattins and Evensong, a really excellent all-in-one version of Midday Prayer or Terce, Sext and None for those with bags of time, as well as Compline, for those who prefer to celebrate Compline in addition to Evensong. All the familiar collects from the Book of Common Prayer are there, plus many others, including a lovely selection of collects for British Saints.
The Customary contains a handy lectionary and for those who are traveling or haven’t the time to get out a bible some short readings for Mattins and Evensong for each day of the week are provided, but one its best features is the selection of non-scriptural readings, many taken from the English medieval mystics, the Caroline Divines and the Fathers of the Oxford Movement.
Although, there is just enough material in the Customary for it to be used with a bible, or even alone, the celebration of the office is certainly enriched by additional readings for some festivals from the standard Roman Office of Readings and the Customary itself suggests this in places. Because it is so very Anglo-centric I find that it also benefits from additional collects for Celtic Saints from our own HCC Book of Collects.
If the Anglican Prayerbook tradition is in your blood then you may find this book an answer to prayer, as I have.