There's enough pics at the Imperial War Museum site, assorted Coastal Command sites to make it clear that ejector exhausts were used for daylight ops.
However, 450 on the deck? "Riiiiiiiiiiiiiiiiight".
Fellow I used to correspond with used to be with one of the MUs testing new airframes - said they dived them to 480 on tests. But then, they were wild young men in them days.