There are three details which show these are not the trousers.
You can see in the promo above that Amy's trousers have two buttons on the cargo pocket. The image on the right shows the Topshop pair, and there are no buttons on the pocket.
2. Rear pockets
Amy's trousers feature full, rectangular pockets on the rear. The picture on the left of the Topshop trousers have either internal pockets with a small fold, or more likely, are fake pockets with a top fold.
3. Leg seam
It's difficult to tell unless you are mega zoomed in, but the Topshop trousers are cropped and have a seam running horizontally below the knee. Amy's trousers do not appear to feature this design in any picture I can see.
Another potential point is the cropping, though Amy wears high-top boots and it's not possible to tell where the trousers hem. We don't get a good enough look at the top to garner any details, however I think I can spot belt loops in the picture above with Rory.
This is all a shame - one less item we have ID'd! It's possible the trousers are still Topshop as they are awfully similar, but there's also a chance it's from Allsaints - it kind of has that look about it, and the top is from there.