challenge: What was the route of the summer through service from London to Porthmadog railway station via Crewe?
  
  A. London Euston, Crewe, Chester, Llandudno Junction, Caernarfon
  B. London Euston, Birmingham Snow Hill, Shrewsbury, Machynlleth
  C. London King's Cross, Leeds, Sheffield, Derby
  D. London Paddington, Oxford, Worcester, Hereford
  Answer: 