The LNER Encyclopedia

In case of interest, I've just watched episodes 2 & 3 of last week's BBC2 TV's Michael Portillo's "Railways Of The Great War", thanks to http://www.bbc.co.uk/iplayer/episodes/b04ddmt3 ; [ At time of writing this, the BBC website says the whole series remains available for 15 days.]

In episode 2 "Railways and Railwaymen Called to Action", at approx. 15m:20s - (and in Ep.3 "Keeping the War Moving", at approx. 10m:20s), - there's a few seconds' clip of B&W cine, apparently taken from above the Down Main on Hatfield station footbridge, looking south, of an approaching express on the DM (behind a pristine-looking loco; "Great Northern" or similar?), also including a few short-wheelbase coaches on a short siding between the DM and the Western Platform line, and the edge-column-supported roof over the Up Slow and platform.

But it could well be from Pathe footage, and so be available elsewhere, possibly as a longer extract.

There's a short 3-4 seconds piece of b&w film footage shot in Welwyn north box (no date given?) and from memory there's a Gresley A3 just passing the box on a Down express the signalman I think is putting the levers back in the frame as the loco & tender are passing the box.

Also there's some b&w film footage of Gresley A3s on both Up & Down express passenger trains passing through Welwyn Garden City possibly during the 1930s & 1940s including a rare shot of 'Hush Hush' heading south through the station hauling a dynamometer carriage, the film footage may well have originated from the nearby Welwyn Garden City film studios because the film footage is all professionally shot.

I can't remember if I've posted this before, but here's a link to a clip of a bygone era at Stevenage. The Great North Road, filmed by Six Hills, was quite busy even in those days.
http://www.eafa.org.uk/catalogue/2475