Why Important
These are usually found in long corridors of larger homes or industrial workshops. These indicate the use and purpose of the original building, and historically important when a building has been subsequently converted or reduced in size. They are important for the heritage context of the whole building.
What to look for
There may be a change in lower wall surface along a long wall. The niche was small, as was the flue, so a built out chimney breast was not required.
When to look
When the initial detailed survey is undertaken. Collect photographs of the existing situation.
How to fix
Clean the cast-iron range thoroughly, and look for casting cracks/failures. It is likely that they cannot be fixed to work again safely, and therefore should be retained a heritage feature of the building.
Avoiding creating problems
As these are rare to find, there is a tendency to remove them and sell them.
However, they could be built into the structure, so removal can cause significant structural damage to the building. Removal is likely to require Listed Building Consent. It may be better to just note that they are there.
Historical background
Builders & Architect Catalogues were often used to select styles for the original building. The Wirral Archives may be good places to research what was available at the time.