Didn't go with the original seat post in the end , there wasn't enough metal there . Did I mention I'm buying as little as possible in , luckily I im a bit of a hoarder when it comes to interesting shaped bits of metal .
This morning my wife put some deckchairs out for the scrap man . They have curves and angles I'm going to struggle to make . They are now on the scrap pile . So bottom line is I have cut up bikes behind the shed and the Dutch granny bike that supplied the steerer tube has also given its seat tube.