The NAMC’s “Catalog of all Series Matchbox Models” (second edition) notes that the red interior of BPW version (variation code 38-2E) comes in two shades of red. This is mirrored by variations 38-2g and 38-2h in the AIM's “1-75 Series Regular Wheels” catalogue (second printing, 1983), although Stannard merely comments "Interiors vary in shade".
The AIM's “1-75 Series Regular Wheels” catalogue (second printing, 1983) also notes that the BPW associated with red-interiored variants can be either thick or thin (variations 38-2f/g/h). However, it is possible this observation simply reflects the tread count which AIM does not report.
Neither Stannard nor Houghton list any new variations.
U.K. Matchbox did not examine the model.