Thanks, Doc.
BIOS was set to non-OS/2
I've run the Unicore BIOS Wizard which produced the following:
BIOS Date: 08/21/96
BIOS Type: Award Modular Bios v.4.51PG
BIOS ID: 08/21/96-i430HX-2A59FG0BC-00
BIOS Eval: Aug 21, 1996 REV.1.11
Chipset: Intel riton 430HX rev 3
Super I/O: Intel 82091AA rev 160 found at port 24h
Super I/O: Winbond 877F (use87h) rev 0 at port 3F0h
As you've obviously realised, this means absolutely nothing to me!