Inside Key Track on the GCR

I first became interested in this matter following a GCRS tour of the former Dukinfield Carriage works, where we were shown a three bolt inside-keyed chair which had been recovered from the site. Dukinfield was not completed until 1910, so this was presumably from old reused rail. I was not previously aware that the GCR had used inside keyed track so I was prompted to look for other examples. Below are some references to clear photographs – there are of course many others, including some where the track is not sufficiently clear to be sure.

Woodhead Part 1, Johnson, p 31 - Gorton old station circa 1900
Shows outside keys in use on main line by 1900.
As above, page 44 - Fairfield old station c1900
Appears to show inside keys on up, outside on down. Transition period?

Woodhead Part 2, Johnson, p 207 - Deepcar Station c1880
Both main lines inside keys. Very deep ballast.
As above, page 214 -Oughty Bridge before 1897
Both main lines inside keys.
As above, page 221 - Wadsley Bridge GC or MSL era
Both main lines inside keys.

Great Central Recalled, Dow, p 47. - unknown location
GC bogie coal wagon. Inside keys, siding.
As above, page 52 - unknown location. Neasden shed?
Loco 169 (4-6-2t). Siding in front of engine inside keys. Turnout and siding on which engine standing OS keys.
As above, page 86 - Ruislip and Ickenham GW&GC joint. Early post grouping.
Inside keyed tracked in foreground. Whose? GC or GW?

This is more a starting point than a comprehensive list, there are a number of other published photos showing inside-keyed track on the GCR, especially in sidings. I have in my possession a print of Ashton in Makerfield showing a train with coaches in pre 1908 livery which probably can be dated to 1900-1910. Both main lines are inside keyed. This line was laid in 1895, although nominally independent but in effect a MSL/GC subsidiary.

On the other hand the London extension was laid with outside keyed track and the GCR had a lot of outside key track, even in sidings, by around 1905. My conclusion is that the MS&L abandoned inside keys round about 1895, and possibly earlier on main lines. However inside keyed tracked survived for many years, especially in sidings, and was re-utilised so it could be found south of Annesley Junction.