The someone in the past that is alleged to have made a mistake is the factory on page 17 of the Tiger’s Workshop Manual.
Others who indicate HEH-B include Taylor in his "Tiger The Making of a Sports Car." On page 101 Taylor references a TIGER II project intention paper which includes HEH-B; then on page 217 Taylor refers to David Barraclough for the same conclusion <reprinted edition>.
Richard Lagsworth in "Tiger, Alpine, Rapier" presents HEH-B on page 137 without attribution.
Clymer’s "Performance Tuning the Sunbeam Tiger" likewise presents HEH-B (page 37), &&& etc.
I’d certainly take Norman’s pronouncement of a correction if one is actually available.
I’ve heard of the dual nature bell-housing but have not seen one. I believe they exist and hook to either a 5 bolt or 6 bolt motor. However such a bell-housing could indicate a number of possibilities, including modification of inventory to fit the 6 bolt motor, for cost reduction purposes…
Rgds,