Thanks as always guys - the hose that came with the car had been butchered to fit so I assume that if the 5e-fhe doesn't have a chamber, the butchered hose must have been off something else. It had a U-shaped chamber between filter casing and manifold.
The replacement hose ( again butchered, but done better ! ) needed to be shortened to fit so I cut away the section of hose which had the outlet for the chamber. The hose now connects direct from manifold to filter casing with no holes or chambers
I think I do remember reading somewhere that chambers like these are used to smooth out airflow and reduce pressure differences in the air stream - might be a load of crap, but I'm sure I remember that from somewhere !