Just downloaded and read the report (Thanks, lobby.)
Was a little surprised to read that the ADC had a PPL issued in'96, as, (with hindsight, of course) it is very easy to perceive how the student could become confused by the instructions issued.
However, it is also easy to perceive from the report that the ADC was in a slight pressure situation with time running out to make a plan and make it work. Likely this affected his choice of wording to the Cessna pilot.
And how do you feel that it is recommended that controllers should take into account the limited abilities of trainee pilots?
At our place, when we have solo (pre-PPL) students, an "S" is written on the right hand box of the strip. There are instructions in the handbook specific to our unit ( sometimes known as "Local Unit Orders") that complicated and conditional clearances are to be avoided to student pilots, and a few other remarks the details of which escape me right now.
It seems to be effective.
Even without the ATCO flying training that used to occur routinely prior the end of the eighties, when cost cutting got real serious. We haven't had any flying training of ATC trainees for a number of years, now.
The local flight instructors are also very "on to it", and before students solo they are exposed to a very wide range of traffic sequencing related manoeuvers, which is necessary because of the range of commercial operations and large speed differences. I would estimate the average student here is probably the equivalent, in traffic situational awareness, to a low time PPL elsewhere, so it's a bit hard to gauge just how effective the local procedure is.
I would also recommend against more than one or maybe two pieces of info/instructions within the same transmission, (ICAO suggest a maximum of three, to regular pilots,) and a nice, slow, even delivery.