British tank stowage item identification

[Lang]

Looks like tis style was not until 1944 and rolled into a sausage not a loose bundle like the mystery item.

[Jakko Westerbeke]

OK, that picture gives us a generic name for this type of stretcher: a “Neil Robertson stretcher”. But looking at those, they all have a lot of longitudinal slats, preventing them from folding like the mystery item, not to mention all the ones I came across have far more straps. I think this clearly shows it’s not one of those.