If any of you have read the excellent book "Dönitz and the wolfpacks" by Bernard (!

) Edwards, you will notice the map at page 90, showing the route of convoy SC 94 from Sydney to the UK. What caught my attention, was that the convoys route went through the Bell Isle Strait, instead of going the "normal" way outside Cape Race / St. John's (as shown on the pic below):
My question is:
1: Why did the convoy select this route, and is this route a part of GWX?
If not; would the Bell Isle strait be to narrow to implement this route?