FWIW I am an MEI, and have been thru the systems in both the US and UK. I thought it was very strange in the UK when they insisted on no bank. It has been demonstrated that bank from 3-5 deg decreases Vmca and increases performance. I have no idea why it is not taught in the UK. Surely the ultimate reference has to be the aeroplane manual. Duh - why would we not want that performance??
If you rely solely on rudder to keep straight you are presenting a larger side surface of the aeroplane into the airflow and hence creating more drag. This drag can be reduced by using a modicum of bank into the live engine thereby relieving the job of the rudder a little and presenting a more normal streamlined shape.
Perhaps someone from the CAA or an examiner would care to illuminate something the rest of us poor sods are missing...
[This message has been edited by Oleo (edited 19 July 2000).]