Yet (based on the assumption that for maximum efficacy of the horde of counsellors involved, a screening process forms the initial stage of the counselling) Prof Wessely's remarks in the article linked in the original post don't support that.Screening soldiers doesn’t protect them from mental illness
You were talking about children and pre-emptive counselling; now you are talking screening soldiers for mental health problems, which is a different topic and consequently Wessley's comments do not apply.
And different populations/topics aside, there's also a world of difference between predictive screening and pre-emptive psychological therapy. It's pretty well known that we cannot predict who out of a bunch of individuals will go on to develop trauma, after experiencing a traumatic incident.
I also said I'd be surprised such a hugely costly intervention wasn't based on evidence - meaning I hold no stake in this, but I'd hope it was - to which you asked how such evidence might be collected.
Anyway - I can't find a link to schools running pre-emptive psychological therapy after traumas - probably just my google-fu being weak, do you have a link please.