This tank was serial number 4034, which doesn't appear in any formal or informal records of tanks in France or elsewhere I've ever seen, so I'd suggest it was just a training tank. Its career as a Tank Bank was short-lived - just thirteen days during March 1918 and it didn't go outside London (unless you count Croydon as outside London). It ended its days as the presentation tank to Kingston upon Hull.
Their presence on this tank is what may have limited its Tank Bank duties to London, though as a presentation tank it still had them.
I see no reason why some tanks at Wool would not have been fitted with unditching rails just for training and experimentation, but yes, generally speaking, Mark IVs left the factory without them and they were fitted in France.
I recommend Dick Harley's recent articles in the tankette magazine. They nicely cover unditching rails and more features of the British tanks of the First World War.
