Blimey, getting the splices to mate up nicely was hard work, it took a lot of fiddling and fettling as there seemed to be big gaps when I held it up to the light. I ended up opening up the V cuts to become flat bottomed and sawing the tips off the points which fit in the Vs.
It was easier to get a fine rasp in there. I tried all the tricks like assembling the joint with a piece of sandpaper in there and the pulling it out to remove any high spots. Eventually with plenty of patience and a several goes at it I got the slice to fit together reasonably well. A pice of flat steel from an old saw blade with sandpaper wrapped around it was useful for getting down to the bottom of the Vs.
I decided to try Resintite adhesive as it's realtively cheap and easilly available and has some gap filling properties, it was going to be that or Araldite precision.
The Resintite is a very fine powder which you mix with water, my wife didn't like me using the kitchen scales as the stuff is a bit toxic I think, so she banished me and the scales to the garage...just as well as I did spill a bit.
I bound the joint with wide rubber strapping (cut from a car innertube, or EPDM roofing sheet)
To apply pressure longitudinally I jammed the bow between a wall and the leg of my shelving, with some scraps of wood as spacers, leaving the middle slightly raised. By pressing down firmly on the middle it forced the joint together. I left it with the middle raised by about 2" which is the back set (a bit like reflex).
I'll take the rubber strapping off tomorrow and post a pic of the joint, you'll be able to see how it has been opened up compared with the pic in the previous post.