In my opinion, Sir Nigel Gresley was the greatest designer of steam locomotives of all time. His LNER Class A3 Pacific locomotive No.4472 Flying Scotsman was the first to travel at over 100mph (161kph) and is still arguably the most famous locomotive in the world. (My father used to work on the A3s and A4s so one of my earliest memories is being on the footplate of 4472 at the Doncaster Engineering Works, known as "The Plant").
On 3rd July 1938, his LNER A4 Pacific No.4468 Mallard recorded a speed of 126mph (203kph) which stands to this day as the fastest steam train ever. 
The A3s and A4s were the thoroughbreds of the British railway network, operating the prestigious London Kings Cross to Edinburgh Waverley non-stop services. They were phenomenally reliable, clocking up several million miles each and still operating the mainline services up until the mid-1960s, a service life of 30-40 years. Three A4s, known affectionately to trainspotters as "Streaks", "Union of South Africa", "Sir Nigel Gresley" and "Bittern", still regularly haul special steam excursions on the British main line, although they are only allowed to run at 90mph (145kph), rather than the 120mph(190kph) of which they are capable. Finally, on 6th February 2016, 93 years after it was built, Flying Scotsman returned to mainline service after a £4.5 million overhaul.
So, that's the history lesson. Now for the cache:-
It is 1946. The wartime years have been hard on the railway system with vastly increased demands and minimal maintenance, especially on the complex A3 and A4 locomotives. The LNER starts a program of repainting its locomotives from the austerity wartime black and renumbers them at the same time.
In the South:-
Hyperion
Salmon Trout
Windsor Lad
Union of South Africa
In the East:-
Silver Fox
Herring Gull / Sir Ralph Wedgewood
Woodcock / Dominion of Canada
Sir Nigel Gresley
Persimmon
Unfortunately, the Big Four railway companies don't last much longer and the railways are nationalised in 1948. LNER locomotives are renumbered yet again, this time having 60.. or 600..or 6000..added to the beginning of their LNER number to form their new British Railways number.
I hope you enjoy the cache. Please bring your own pen and leave the cache exactly as found. Although there is room for trackables etc., please don't leave any as the cache is set up in a particular way to give a particular effect. You'll see what I mean...
Incidentally, you may think of this as ancient history but, in 2008, enthusiasts completed a new build of a Gresley-inspired locomotive, the Peppercorn A1 Pacific, 60103 Tornado, and the latest of Gresley's most powerful locomotive class, the P2 2-8-2 Mikado, 2007 The Prince of Wales, is currently under construction and due to be completed in 2021. I also recently learned that the 4-6-2 (Pacific) wheel arrangement for express locomotives is so-named because it was pioneered right here in New Zealand!
NOTE:- This geocache is quite fragile so please be careful with it.
