I am not quite sure who gave me this commemorative cover or indeed who produced it. I suppose that it could have been the then Limavady District Council which had the idea of celebrating this little known event. It does seem to be slightly unusual to celebrate a fourteen hundredth anniversary. It's not one of those anniversaries that strike you as being particularly noteworthy.
The Convention was called by the then High King of Ireland a gentleman by the name of Aedh (aka Hugh). There were three matters deliberated upon:-
1. The release by Aedh of one Scannlan Mor. - He wasn't!
2. The growing and burdensome power of the Bards. - Their powers and numbers were reduced.
3. The relationship between the High King of Ireland and the Scottish Kingdom of Dalriada. - The Scottish kingdom no longer had to pay tribute to Ireland and a mutual defence alliance was established.
I suspect that this piece of ephemera will end up on e bay or in a postal philatelic auction in the very near future.