Help Me Identify This Image Please.

The article discusses the fact that on one side of the engine the moon initially faced away from the deer, but was then changed so that it was the other way round and the same on both sides, and asks for dated photos so that the date of the change can be established. I have been unable to find out the significance of the deer-moon symbol itself (so far).

There's another page which lists the designs on other steam locos; it seems that the swallow design in various forms was found on a number of different locos, in some cases faked up with silver foil or painted on by the engineer!