I have just checked my model and both crests are facing left.
I have also checked through the following book that is a great read "The Great Western Railways Gas Turbines, A Myth Exposed" by Kevin Robertson, at the photographs that are in aforementioned book and all the pictures do show that the BR crest is facing to the let on both sides.
I am not sure if the book is still in print but I have just done an internet search and you can get it on the second hand market. This also covers the other gas turbine locomotive 18100.
Terry