What was Steamport, Southport
The starting coordinates are out of bounds and you will probably be arrested for tresspassing, so don't go there.
However this is roughly were the steam trains used to take the passengers/guests to & from the museum, for a little ride on a historical steam train.
Southport MPD (Motive Power Depot) is a former LMS railway depot located in the town of Southport.
History - Derby Road shed first opened in 1890 under the ownership of the Lancashire and Yorkshire Railway. In January 1935, under the ownership of the London, Midland and Scottish Railway, Derby Road was given the shed-code number 23C, which it was to have for the remainder of its days under the LMS and for the first two years of British Railways ownership. From 1948 Derby Road shed became part of the Liverpool Bank Hall area and, in June 1950, the shedcode was changed from 23C to 27C.
Following the amalgamation of the four pre-grouping companies into BR, Southport shed was given the code 23C, in 1950, and was to be one of the sheds in the Liverpool Bank Hall area. The shedcode 23C, however, would not last for too long, as the Liverpool Bank Hall area number was changed to 27, from June 1950, with the Derby Road shed code being changed to 27C at the same time.
The main locomotive allocations to Derby Road shed over the years were LMS Black 5 4-6-0s, including the two Caprotti valve gear Black 5s Nos. 44686 and 44687. Alongside the two Caprotti-geared Black 5s were two other engines which would later be preserved, 44767 (the unique Stephenson valve gear Black 5) & 45337, which were allocated to Derby Road in 1962 & 1963 respectively. As well as the Black 5s, other class allocations included: BR Standard Class 4 4-6-0s, LMS Compound 4-4-0s, LMS Fairburn 2-6-4Ts, LMS Fowler 2-6-4Ts, LMS Fowler Class 4F 0-6-0s, alongside numerous pre-LMS machines.
Final years under British Railways - In September 1963, Derby Road's shed code was changed from 27C to 8M (and the shed was transferred from the Bank Hall section of Liverpool to Edge Hill), which it was to carry until the shed's final closure in June 1966. During the time when diesels were taking over from steam engines none of the then-modern diesels were allocated to Derby Road's 27C (later 8M) shed. Allocation of steam engines to the shed ceased in November 1965, and by the end of the year just seven engines were allocated to the shed, these being three Black 5's and four Fairburn tanks. The majority were transferred to other depots, with one of the Black 5's (one of the Caprotti geared Black 5's), No. 44687, being withdrawn from service. The depot closed on Monday, 6 June, 1966, with the final engines being removed from the site by the 18 June.
Steamport, Southport - Derby Road shed closed completely in 1966, prior to the withdrawal of steam traction on the British Railways network and, alongside being stripped of recoverable materials, the building was also heavily vandalised over the years. In 1971, a group was established with plans to start up a museum in the former locomotive shed. The building, however, was heavily in need of repairs as there was no track in certain places, the yard was covered in rubble, the shed building had no glass in the roof, the electricity and water supplies had been cut off and BR had severed the rail connection to the shed.
Southport Railway Centre (SteamPort) closed in December 1997 and most of the stock moved to Preston docklands to become Ribble Steam Railway.
Following the closure of the museum, the shed and additional buildings were demolished to make way for the new Central 12 shopping park, which would be built on top of the former shed. (You have probably parked your car where the museum once stood). Nothing remains of the shed today, apart from the former gates opposite the Bacon Factory at Windsor Road, which are visible from the footbridge.

Waleswood at Steamport Southport 1978
The coordinates for this cache can be found by answering the following questions from the information above (assume N53 & W2) :-
N53
J = Derby Road shedcode was change from 2JC to 27C
K = Derby Road first opened in 1K90
.
L = Caprotti valve gear Black 5s Nos. 4468L and 44687
M = In June 1M50, the shedcode was changed
N = Diesels were allocated to Derby Road's 2NC shed
W2
V = These being three Black V's and four Fairburn tanks
W = In September 1W63, Derby Road's shed code was changed
.
X = Derby Road shed closed completely in 1X66
Y = In 197Y, a group was established with plans to start up a museum in the former locomotive shed
Z = Southport Railway Centre (SteamPort) closed in December 19Z7
N53 JK.LMN W2 VW.XYZ

Nuttytart - FTF
(Info from Wikipedia)