Good links, thanks! The IBM was known as Phoenix https://en.wikipedia.org/wiki/Phoenix_(computer)

I spotted Maurice Wilkes (middle person in the top two of https://www.cs.kent.ac.uk/people/staff/pfl/photos/cambridge/...) and I might be wrong about David Wheeler (top of https://www.cs.kent.ac.uk/people/staff/pfl/photos/cambridge/...) and Roger Needham (top of https://www.cs.kent.ac.uk/people/staff/pfl/photos/cambridge/...)