Well - not entirely OT. I did assemble and modify the base myself!
Towards four years ago we bought a Millbrook mattress - and have been very satisfied with it.
Needing a mattress for another bed we decided to buy another one. Of course, various issues mean it is not identical but is similar spec. It arrived last week.
On opening the packaging, there was quite a strong smell. We did not get this with the original mattress but nonetheless thought that it would soon dissipate. The smell is still there. The room has had the window open most of the time. The bedding that was put on it also smells. The room smells.
We think the smell is very like that of untreated sheep's wool - with the lanolin still on it. (The mattress does have wool as a component.) But various internet sources suggest that mattress smells are often due to flame retardants.
Of course we are raising the issue with the supplier and manufacturer. But in the meantime thought I would ask if anyone has had a similar experience? What they did about it? Did anyone identify the source? What is a reasonable length of time to have to wait to use a new mattress?