Remember the Arnos Park viaduct mystery? How many arches did it actually have? Here’s another London Underground Piccadilly line viaduct mystery. And this time the answer is a balls up…
Let me explain. Arnos Grove station has an exhibition on its footbridge detailing the history and construction of the station and the Piccadilly’s extension to Southgate/Cockfosters. There’s one picture interests me. Its claimed to be Arnos Park viaduct. Is it really? Its the wrong viaduct pictured in fact!

Anyone reading the information panel in question would understand its the viaduct at Arnos Grove shown in the picture at right.
This viaduct depicted is certainly long and curves.
But is it Arnos Park viaduct? Nope. Not in a million years!
Its actually Southgate Viaduct!
Whaaaat…! But the information says “The image on the right shows men working on the construction of the elevated tracks between Arnos Grove station and Southgate station in April 1932.“
The viaduct between Arnos Grove and Southgate is indeed Arnos Park viaduct. But the picture shown in the right hand panel is actually of Southgate viaduct! Look at it more closely….

The picture actually shows Southgate Viaduct!
Houses in Winchmore Hill Road and Hillside Grove can clearly be seen as well as the substation itself. Those in Hillside can still be seen today as the next two pictures shows. Mayfair Terrace in Southgate had not been built at the time of the viaduct’s construction.

Self explanatory picture showing the houses and substation from Southgate Viaduct.

The same houses in Hillside Grove with Southgate viaduct on the left. Source: Google Streets.
The information board tells passengers (oops customers) to look at the LT museum site for more details. Here’s a screencap of the relevant photograph on the LT archives below.
As the LT museum text says, the view looks south “towards the site of Arnos Grove underground station.” The problem is Arnos Park viaduct curves to the east if one is looking south. The one shown curves to the west so its NOT Arnos Park – not even in a million years!
What is this “station building under construction?” They claim its Arnos Grove station. No! Its the substation in Park Road Southgate, under construction!

Screencap of the erroneous photo and detail at the LT museum photo archives. Link.
It seems LT (or TfL) can’t recognise substations built in 1931-32 as part of the extension to Cockfosters for its being claimed the building under construction is Arnos Grove station.
The structure in question is in fact the Park Road sub-station to the north of Southgate station. If one wants to find the sub-station its right by the southern end of Southgate viaduct and just a few minutes walk from Southgate station.

The ‘Arnos Grove station’ in question – its actually the substation by Southgate viaduct – as seen from a passing train.
Both the LT museum and TfL should have sussed this picture was absolutely wrong. Its not even the one they claim on the information board or on the archival website. Its Southgate viaduct yes, Arnos Park viaduct no, never, nada, not in a million years!
Update August 2018:
TfL changed the poster depicted at Arnos Grove station! Whereas the original indicated the viaduct pictured was Arnos Park viaduct their new poster in essence denotes it as Southgate viaduct.

The original format display poster with its erroneous text. The viaduct pictured certainly isn’t that at Arnos Park.

The original text close up – this denotes Arnos Park viaduct as being the structure pictured in the right hand panel.

The new poster format – same viaduct in right hand panel, however the text has been corrected to an extent & now says ‘construction of the Piccadilly line along a viaduct near Southgate station….’

The same panel in close-up with its corrected text.