I believe it was compiled by those Anglicans who were Anglo-Catholic and wanted materials to supplement the Book of Common Prayer so that it was possible to celebrate a more 'Catholic' rather than 'Protestant' Eucharist. It took materials from the then pre-Vatican II Roman Catholic liturgy but in English translation. I do not think it is very widely used anywhere any more. Although an Anglo-Catholic I have never seen it used. Before the bishop swept in and closed my parish when our last priest retired, we used to have some of our liturgies according to the Book of Common Prayer (BCP), and when we did we followed the BCP. We never used the Anglican Missal.
Basically, the 19th century crisis of theology led to the creation of the "Catholic v. Protestant" distinction. By 'Catholic' was understood 'the church as she always was' best exemplified by the Church of Rome. By 'Protestant' were understood the various churches coming out of the Reformation, but especially the Methodist, Baptist, and Evangelical streams which were very successful in terms of numbers. They cared nothing about 'the church as she always was', believing that the Church was corrupted immediately after the apostles, so there was nothing to recover. But their overflowing numbers proved that you didn't need to be a historic church in the first place. So you had these two fundamentally flawed categories, and they defined all of Western Christianity in the 19th century. You were either a "Catholic" (whatever that means), or a "Protestant" (whatever that means). And to any responsible Christian, especially to Anglicans to whom history is so important, there was an appeal to the "Catholic" label. Which basically meant, "something like the Church of Rome". That's why you had John Henry Newman simply convert to Romanism, because why not just go for the full thing? Others who remained within the Anglican tradition, still tried to LARP and grasp for straws at how they could resemble the Roman church without converting. Thus they added incense, various Roman traditions and vestments. And finally came the "Anglican Missal" and effectively the rejection of the Book of Common Prayer (then castigated as "too Protestant" ). This LARP dress-up came to an end, first after Vatican 2, but even more so in the last 20 years with the collapse of the Church of Rome. It is very hard to LARP as "something like the Church of Rome" when its priests have clown masses and lavender/rainbow vestments.
It has additional collects and lessons for black letter days, but you could get those from Lesser Feasts and Fasts. There are also some introits, Bible verses related to the feast. I don't have a copy at hand, so I'm not sure what else it adds.
It is interesting in my area the is a new Parish, more generally part of the Independent Catholic Church of Brazil, and under the patronage of Our Lady of Wallsingham. The rite they are using is English Missal, and the BCP Lectionary. I have been, however they are a little too far for regular attendance. They do however conduct the liturgy beautifully, with much solemnity and sufficient incense for the occasion. I am not commending, just sharing the interesting odd reality of Church in the 21st century.
I have read some odd things about the ICCB. Anyone have more information on them? From what I have read they are kinda heretical.
Their doctrinal positions fall in line with the Old Catholics, generally. Although they permit the clergy to marry. However, they are notorious for getting involved with indigenous (animistic) religion in ways which most orthodox Christians would consider unacceptable, perhaps even being involved in sorcery or necromancy. Masses for the dead: That section of the Missal contains some special content for All Souls Day as well as a couple of forms of Requiem Mass and observances of the anniversary of someone's death. Some of this content is meant to be used as private masses, which is something the reformers were in general agreement against and lends support to the perspective that the book is a crutch for those who want to be Roman without going through the formalities of doing it the licit way.
However, they are notorious for getting involved with indigenous (animistic) religion in ways which most orthodox Christians would consider unacceptable, perhaps even being involved in sorcery or necromancy. Yeah it is this part I find disturbing about them to the point I would not want to have anything to do with them
The Australian version is hyper conservative orthodox with a substantial dose of former Anglicans. In the main its members are members who would still be Anglican save for (and there are a number of reasons that get added there). The clergy I know involved are certainly Anglo Catholic if not verging Anglo Papist. I think one of the attractions is that they can been connected to the Pope and still have the Pope not infallible. I have seen no evidence of sorcery or necromancy in the local expression. I of course have only a limited understanding of a local congregation and they may well be little resemblance to the group in other places. I should not imagine that two many of their congregations would be using English Missal.
I believe that link occurs only in those dioceses which abut the Amazon rainforest. The ICAB is a difficult group to investigate because they fall in and out of relationships with Spanish speaking neighbors with some regularity. There are groups claiming a link to the Brazilian mother church that are not actually recognized by her. Of course, when you are essentially independent and only claiming to be linked to a particular church you can do whatever you want. (I was reading recently that Brazil has the largest population of uncontacted indigenous people in the world.) On the Missal, interestingly, one of our Puerto Rican clergy recently informed me that there is a Brazilian bishop publishing a Spanish translation of the Missal. He asked me if he could order a couple of the altar books for his use in public celebration, to which I replied: why are you asking me? I am not your bishop ordinary.