I thought I'd sent over a couple of pictures of my Mercian tt frame. I've not seen too many (any) like it so assume it wasn't a standard frame that you produced. It's an early nineties frame I think, recently refinished and turned into a fixed wheel bike via a White Industries Eno hub (all the braze ons etc left in place for changing back in the future).
It's somewhat aggressive to ride, and I can't honestly say it's all that uncomfortable at any distance over ten miles (though I've ridden London -> Brighton on it…). It is incredibly fast and lairy to ride though, and by a distance theprettiest bike I've got.