This information (April 2007, C Winter) supports the view that the tree swing cartoon was circulating in UK offices in the 1960s, if not before: "In 1969 I worked for the Customs & Excise in Southend writing the original VAT accounting system. At that time, the Civil Service had a regular internal newsletter called 'Red Tape'. I have a page extracted from a copy of that newsletter that has at least six of those exact tree swing pictures..."

More recently I received this recollection (thanks S Hytche, 29 Oct 2010): "As a college student back in 1968-69, I worked part-time in IT key punch operations. The tree swing was around then to show what end-users got from 'systems people' and to make the point that the users needed to be involved in all phases of the development process..." (This logically refers to the 'IT Project' version of the tree swing cartoons, rather than the 'marketing' version, or 'teacher' version, which is shown below.)

And this submission (May 2007, thanks Mark Linton): "...I have a copy of 'variations on a tree swing' that was printed in the San Franscisco Examiner on Sunday, October 12, 1975, with the accompanying text - 'A sometime publication, The Teaching Paper, is produced by Portland teachers who somehow have escaped the smothering coccon of pedagogy. In this excerpt from their admirable sheet, they cast a bemused glance at the befuddlements of a bureaucratic school system and composed a hypothetical example of how various school entities would face a minor construction problem...' "