For a JAR-FCL Class or Type Rating, if the relevant revalidation requirements can be met in an appropriate simulator by a LPC, an SEP Class Rating 'training flight' is not required - provided that the 'experience' requirements are also met. Somewhat daft, but there it is.....
But for the National aircraft Class Ratings included in a NPPL, the stipulated requirement will be for a minimum of 1 hour's cumulative flying training.