Paul, you didn't find it because it isn't in the testimony at either inquiry. However, by using the details given by Rostron and a bit of work with the traverse table, we find it was 41° 10 N, 49° 12' W.
By following Rostron's evidence, we also find that it was wrong by a few miles. No harm in that. Probably Rostron was getting more help from the North Atlantic Drift than he thought.