Well.
Another weekend wasted being a geek
So I wrote a circular buffer and took on board (but didn't implement exactly) the Disruptor pattern. I've written a test harness which I will post soon once it is presentable so that we can optismise with the full brain power of Lavag.org rather than my puny organ (fnarr, fnarr).
In a nutshell, it looks good - assuming I'm not doing anything daft and getting overruns that I'm not detecting.