This thread sure takes me back to my first glider solo in August 1958 with 616 at Henlow in WT901. I was the first 616-trained cadet to solo there as Peter Bullivant didn't open the school until the July. An advanced course at Halesland in 1959 then a staff cadet and CI with 616 until the end of 1964.
I do recall one instructor who gave a trainee a simulated cable break at about 100 ft. The launch was, maybe, a bit slow and after the instructor 'pulled the bung' nobody seemed to do anything. Eventually the instructor pussed the stick forward, but it was too late. The T31 mushed-in and landed with hard. Fortunately the trainee was unhurt, but the instructor had a back injury which landed him in the RAF Hospital at Halton.
I'm fortunate that I still get to fly a T21b regularly but would love another 'go' in a T31.