I lived in Britain for 12 years. 1989-2001. South east London commuter belt, along the Charing Cross mainline to Hastings. (Bopeep Junction and tunnel if you want to get technical, from my Rail Atlas Great Britain book that one REALLY needs if your going to even START to figure out all the rail lines in this vast little country). I never took a number per say in a book, but when taking pictures(slides), I'd always get the number of the lead engine in the U.S. AFTER I had taken the picture to note on the slide. Rail fanning for me was chasing trains to photograph, all mostly in California from, 1975 to present day. The first time I encountered a British Railfan, he did not have a camera, but a HUGE binder. He may have been anyone of those children in the video. Guy was pushing sixty, lumping around this giant book of NUMBERS. We got to talking as you do and he said he collected numbers from rolling stock. Locomotives(Steam, Diesel, Electric and Underground stock), Carriages(Passenger, Freight), M.O.W. (Loco's, rolling stock) and Preservation rolling stock. He could trace a freight car from new to scrap yard, every number it had wore and every paint job it had had and he could do that now, with every number in his binder. Dates back when he first started in the 1950's, to present day. One steam engine he showed me, starts out in Southern Railway paint-Southern Railway number, to British Railway number, to re-paint, to a name and new number, to preservation and another paint job back to Southern with a new bell. I MEAN GEZZZZ! But, see that's what floated his boat. Great! What do they call em over there? Bobble Heads or Anorak Men. All down to their attire.

Thing is, you can't easily chase trains in Britain or Europe. A) They go to fast. Be it Passenger or Freight B) They slice through private property far from nearby lanes that hardly ever follow the tracks anyway. C) Are all fenced of with barbed wire. D) Platforms are policed and some depots and large Stations require one to have a Platform ticket to even be there. The time I spent track side evaporated. The wife and I would return to California or other parts of our country and I'd get my 'Train' fix then.
I noticed Uncle Pete has begun to Fence off access to J.R. Davis yard here in Roseville, Calif.. Six foot of a dense shiny steel wire mesh, with a sharp top. Well. That blows off pictures with out a ladder now. I mean. Who does that? Our society,law and court system has changed it for our simple hobby but being the truly vast country we are, we'll never be Bobble Heads, thank goodwin. Well not in my lifetime. But yeah. That's how they do it over there. I can see em all now....