Thank you all for your input: I am now aware that there are deep feelings at work here on both sides of a thorny issue. Thanks particularly to Fr John Abberton; your courtesy in dialogue with people who didn't put their names to what they had to say was admirable, and your argument charitable despite strong opinions on the other side.
As in all these matters, I am thankful that the Church does not require belief in regard to private revelations, and that, as Vatican II declared, no new revelation is expected from the death of the last Apostle until the second coming.
I now think better of those Anglican clergy extending the invitation, though I still deplore the discourtesy involved in doing a mailshot of the priests of our diocese while bypassing our diocesan hierarchy who might well (=almost certainly) have had something to say on the matter. It is ecumenically insensitive, to say the least. And using the words 'authentic and authoritative' is highly misleading, however modified by writing that this is [merely] the opinion of the signatories. It suggests to me that the Rev. Gavin Ashenden and his fellows do not have the same understanding of 'authentic and authoritative' that the Catholic Church does. Once more, it appears to imply the Reformation understanding of private interpretation as being authentic and authoritative, rather than the judgement of the Church to whom the Lord promised the Holy Spirit to lead us into all truth.
I shall not be attending the meeting at Chichester Cathedral. There is enough gentle dissuasion in the CDF documents to suggest that this would be the better course. There appears to be a dubium at least on the issue of these—what word should I use—maybe possible revelations. However, thanks to Fr Abberton, I shall not think badly of any of my brethren who will go.
And, as a matter of fact, I can't go: I shall be flying from Canada to the USA on that day. But I'm still glad to have been informed of the issues, and all those who participated have my thanks.
I am, by the way, still happy to post charitable and articulate comments on this subject.