Since I raised the question, I thought I'd best attempt to answer it! Here's the 35mm trailer scan vs. the Blu-ray and PAL DVD:
I should stress that this isn't an identical frame - the shot as used in the trailer is cut at completely different positions, so there's no overlap - but I estimate there's about a 5-6 frame difference here.
The DVD, as expected, is the most conservative of the three, while the Blu has the most picture area in general and the film scan sits somewhere inbetween. I presume the folks who scanned the film* captured every possible shred of picture information; perhaps more than would have realistically been projected. So the previous assertion of a-bit-more-than-the-DVD seems pretty much on the money...
*Since the trailer came from the other site they might wish to keep a low profile here, but I'll certainly credit them if they like!