Two Bristol MR.1 were built:
A5177
A5178
One of these two later became A58623, which is well-photographed.
The new Air-Britain book "Bristol Fighter" says it was ex A5178.
However, most other (older) sources (eg Putnam) say that A5177 was the machine that became A58623. BAE Systems Heritage also go with this version:
www.baesystems.com/en-uk/heritage/bristol-13-mr1-all-metal-biplane
Can anyone please confirm which is the correct version?