Network Locked SIM card on Unlocked Note 9
OK Digging around found the solution.

Samsung devices have a regional warranty lock, I needed to make a 5-10 minute call to a local number using the Tesco SIM to unlock the phone for use with networks outside that region.

It is clearly printed on the box, but Tesco helpfully put thier own welcom to Tesco mnobile sticker over this.