So details first 
Fully serviced with 62k miles 
2007 HR 
fault codes P0000 nil 
  
What happened: went to tesco, came out and would Not turn over - starter gave one dieing groan for a second and stopped. 
  
What I did: suspected battery although it was showing 12v, jumped off another car - no difference 
Bought a new battery no difference 
Recovered back to my drive 
  
Next: starter off and tested, tested OK 
Tested continuity in the cable from the battery+ to starter, all good (very minor surface corrosion) 
Checked ignition fuse next to the battery, still intact 
  
At this point I'd like to say: 
All my keys still unlock and lock the car remotely and extinguish the immobiliser led 
Fuel pump can be heard to prime 
Upon key to start, nothing at all from the starter 
  
Now I'm suspecting maybe continuity in the cable from the ignition system? 
Blown relay? Not sure how likely that is 
Another fuse I'm unaware of? 
  
Any suggestions are welcome