When I was at Wattisham I worked with two fellow Riggers whom were at Bruggen at the time of the wing folding incident. I seem to recall that only one outer wing folded; the other being correctly locked down.
In all the rush nobody spotted that the wing fold lock tell-tale flag was (obviously) still sticking up.
I believe that after this incident all the tell-tale flags were painted day-glo orange.
After hearing their tale I always gave the wing a huge waggle during BFs and TRs!