I was the Provisions Manager at Trinity Street in the early '70's and remember the System 25 as it impacted us in the branches.
We were provided with two ‘Data Capture Equipment’ units manufactured by Plessey and these would be trundled around the shelves recording the ‘B’ and ‘C’ products identified on a bar coded shelf edge label.
This was huge improvement as It replaced a manual paper printout system which was painstakingly relayed to Blackfriars IT department, over the telephone, each evening, one page at a time, which took ages to complete during the allocated evening time slot we were given.....that is when you could get through on the phone!
The Plessey system was a big improvement although as the machine’s keyboards began to wear it was common for keys to 'bounce' when pressed and you could end up with 33 cases instead of 3 if you weren’t careful! Sometimes the depot would ring to clarify but often not……a case of ‘garbage in, garbage out!’……..typical of early computer systems.
On completion of the ordering sequence they were trundled to a dedicated parking area where they were plugged in the recharge the on-board batteries and connected to the modems which were the size of small suitcases!
We did, however, dread the often regular occasions when a glitch happened, e.g. modem lines being faulty, and then an ‘Emergency Order’ would be generated by Blackfriars based on previous orders. These were notoriously inaccurate and produced many ‘Overs’ that had to be sifted out daily before that days ordering to relieve the buffer room storage area being compromised.
I also remember the time when the customer trolley cleaning contractors arrived to be told "steam clean everything with wheels" and they diligently did so...including the Plessey units!!