Not 'big' ICL here, no mention of 1900 or 2900 series mainframes, or mention of my time as an operator on a dual-node 2966 mainframe back in 1983 :)
No, this is 'little' ICL - the side that got involved with Sinclair Research sometime in 1985 or so to produce an office based ruggedised version of the Sinclair QL. And here's the fruits of that partnership - the OPD or One Per Desk, designed to take the place of the clunky CP/M machine (or IBM PC) and the office phone, so you could be doubly productive! Or perhaps not. I still use one for my main house phone, despite their age they're tone-dial compatible, the only thing they object to these days is a long phone number like one that's a result of dialling a robot answering service ("press 1 to get annoyed, 2 to get fobbed off, 3 to end up in a dead-end" etc)
A strange hybrid of a Sinclair QL CPU and ULAs, 2 ruggedised microdrives, a real keyboard and a small 2 line phone exchange, power was fed from the monitor and that's the only place you'll find a power switch - the base system was designed to be left on out of office hours to answer the phone with either a data call or a predefined voice message that could be built up from a vocabulary of 154 words, resulting in "hilarious" messages like "My Secretary is giv_ing me head in the office on holiday" :o)). All the software was in ROM, and with the addition of the Xchange module the original 4 QL applications could be used in an unique multitasking environment.
There wasn't an Operating System per se, rather an environment called BFS which ran everything and handled the different tasks. Despite the fact the OPD was only manufactured for 3 years there were a surprisingly large number of applications and peripherals made for it, including 3 1/2 and 5 1/4 inch disk drives, ROM modules and expansion units like the ICL MEU (Memory Expansion Unit).
Sadly, or typically, it was crippled by complete incompatibility with everything! While QL and Spectrum microdrive carts could be formatted on the OPD and used they then couldn't be used in anything else, meaning no easy data transfer from or to the OPD. In addition, despite the fact ICL engineers had rebuilt the microdrives they were STILL unreliable enough to be a pain. The serial port only transmitted to the optional OKI printer for reporting purposes.
One Per Desk - technology well ahead of its time - a combined workstation and 2 line phone exchange! BT Merlin M1800 - from Richard Harding....see above :)
Merlin Tonto with destroyed innards but beautiful externals!