There is data in the report regarding RPM, albeit from an analysis of the action camera audio, and JPT as viewed on the cockpit video data. The relationship between the two was consistent and, therefore, there appears to be nothing to suggest a bleed valve problem. This is probably why it was not analysed or investigated further. With a 100 series Avon the normal manifestation to the pilot of a bleed valve malfunction is a low JPT for a given RPM when at a high value. The pilot does not have a thrust meter and any differences in acceleration due to a variation in thrust are subtle and may not be noticed other than by an acceleration check on take-off. The only guaranteed indication to the pilot of an Avon 122 with a bleed valve stuck open is a JPT of less than 560 C at maximum RPM.
For those who seem to be intent upon trying to identify an engine malfunction I would like you to consider the fact that the aircraft reached the apex with sufficient airspeed to enable an escape manoeuvre to be flown safely even with idle thrust which is not significantly greater than the zero thrust from a flamed-out engine. And it would be an uncanny co-incidence for an engine malfunction that caused a significant reduction in thrust to occur during a manoeuvre which the pilot entered at an airspeed less than the minimum planned and during which he also failed to perform an escape manoeuvre despite being significantly below the gate height.