Checking where people are coming from to find this blog, I stumbled across a thread on Catholic Answers which raised an issue I've seen a few times recently under various guises, namely whether we can be 'doing liturgy' when we say the traditional Benedictine Office.
The Office can be said either as a devotion or as liturgy. As a devotion, there is no issue about approved versions, rubrics etc - essentially it is a matter of do as you like (within reason of course)!
As I think there is a bit of misinformation out there, however, let me reiterate a few points here. Firstly, lay people can, in principle, say the Office liturgically, regardless of whether a cleric or religious is present when they do so.
Secondly, contrary to some claims, the traditional Benedictine Office, with its traditional calendar, using rubrics and calendar approved in 1962 (and very similar to, but not identical with, the 1962 Extraordinary Form calendar and rubrics), continues to be officially approved, and is used by quite a few monasteries. The Farnborough edition of the Diurnal follows that approved form.
It is true that in 1979 the Benedictine Confederation approved a series of revised options for the Office. However, from 1984 onwards a number of monasteries received explicit permission through the Ecclesia Dei Commission of the Holy See to retain the traditional Office, Mass and calendar (in line with the permissions for the use of the traditional mass more broadly).
In 2007, with the Motu Proprio Summorum Pontificum, the permission to use the traditional forms of the Mass and Office for the Roman Rite was generalized to all clergy wish to use it. The Ecclesia Dei Commission has indicated that this also extends to the rites and uses of religious orders. Accordingly, there can be no doubt that the traditional Benedictine Office as set out in the 1962 Monastic Breviary is approved for liturgical purposes.
There are though a few issues that do need to be considered in relation to the Diurnal.
First, while the Latin clearly has ecclesiastical approval, it is not clear whether or not the particular English translation included has approval for liturgical purposes. An edition of the Diurnal from 1963 using the same text did obtain an Imprimateur, but I haven't seen the detail of its terms, and the English may have intended to be used for study purposes only. Moreover, the Instruction Universae Ecclesiae specifies in relation to the Roman Breviary that it must be said in Latin.
Secondly, the Farnborough edition of the Diurnal lacks an official attestation that it is published in accordance with an approved edition (CL 826).
Whether either of these issues is sufficient to render the saying of the Office from the text in English devotional rather than liturgical is perhaps still debatable. But in the light of Universae Ecclesiae, the safest approach is to say the Office in Latin, and use the English as an aid to understanding.