Houstoun (aka Ulston or Uston), Par. of Jedburgh, ROX, SCT
This place (as Houstoun/Houston) was a bit of a mystery to me, and in my ignorance had assumed the transcript I was reading had misread Howden. I've seen the light.
Reading the actual baptismal entries made it quite clearly Houston or Houstoun, and then for the last child of James Shiel, there it was as Ulston. The penny dropped.
Web searches found me 14th century references to a Roger de Uston and an article on the Ragman Roll, of 1296 to Symon de H(o)uston and my trusty Groomes has an entry for Ulston which pointed me straight back to Jedburgh (1¾ miles NE of Jedburgh itself).
Groomes also had a reference to Houston is to a place in Renfrewshire, which is obviously not the one being referred to in the Jedburgh OPRs.
Google maps failed me as not being detailed enough, but the Ordnance Survey Landranger 74 for Kelso has it showing as a small cluster of buildings just out of Jedburgh, also with an Ulston Moor nearby with a roman road going through it.
I guess I'll quickly be able to spot the databases online that have copied my incorrect info here, anything with Shiel births/baptisms in Howden!