At the beginning of this thread I suggested producing a timeline for the Dynamometer Car. Having changed tack at various points through the original postings here is what I believe to be the timeline for this vehicle and its livery at various points.
6th March 1906: First test - R Class 2109. Vehicle is in NER Crimson Lake livery which means both the sides and the ends are in Crimson Lake, and the various panels on the side and ends are lined. Running number 3591.
18th Oct 1923: Last test in NER livery - C11 no 878
9th June 1924: Repainted in imitation grained teak and given a slightly modified form of the NER lining to sides only. Relettered and rebranded "LNER" with running number 3591Y.
26th June 1924: First test run in LNER guise - GN Section 4419
3rd April 1928 - 25th Aug 1928: Gresley type bogies fitted and corridor connections added with end grill protector hinge positions swapped. Number changed from 3591Y to 23591. Still imitation teak with lining present.
26th Sept 1936 - 19th April 1937: Duckets fitted. H M Lane's photo would suggest that the ducket protection grills were in place at this point, however they were not visible at Mallard's speed run. Livery unchanged from earlier as emulated here:
3rd July 1938: Mallard's speed run.
4th July 1938 - 29th May 1946: In storage. Probably renumbered 902502 with grill protectors added to protect the ducket windows before re-entering service. Once again only the number panel appears to have been altered, the rest ofthe vehicle is still lined.
30th May 1946: Test runs with locos 484 and 1766 listed as practice runs and for staff training.
26th and 27th Feb 1948: Dynamometer Car sent to Derby to be re-calibrated along with the GWR and LMS cars
8th Apr 1948 - 3rd Sept 1948: Locomotive Interchange Trials. These were the first tests to be reported direct to British Rail. On 29th July 1948 the interior temperature of the vehicle was recorded at 93 degrees Fahrenheit.
4 Sept 1948 - 11 Nov 1948: Given full repaint in imitation teak but without lining. Branded as British Railways E902502
12th Oct 1951: Last test - Hunslet 500HP Diesel.
Latter half of 1963: Sent to Darlington for preparation for display in Clapham. Likely to have only involved regraining the panels containing lettering. LNER lettering restored. The "Dynamometer Car" lettering is not quite in the same place, it being incorrect on both sides. The photo above has been altered to show the correct lettering position.
If anyone would be kind enough to volunteer the use of one of their photographs of the "Dynamometer Car" lettering on the other side of the preserved vehicle, I will digitally reposition the lettering to reflect its correct position and post a comparison image.
P.S. At various points the measuring wheel did appear to be painted white when emerging from the paint shops, however as previously commented it was not evident during Mallard's run instead being covered in dirt.
Edited: Dates adjusted following drmditch's post below.