It wasn't so much the downwash as the decision to carry out a very shallow approach, at rooftop height, over the residential area! Best approach (clear of houses) is from the East (noted in the RAF AIDU Flip)
I've spent years keeping those residents informed and content with regard to helicopter downwash around that HLS, (the main hospital HLS in Lincolnshire) This incident literally blew that goodwill away!
Several hospitals would dearly like to get rid of their HLS's and build on the valuable land. (Some already are: QMC, the biggest trauma centre in E. Midlands, builds over its HLS next month. Helicopters bring in expensive trauma from a wide area. Hell! we bring them work they don't want!!
Events like this one simply give extra ammunition to the anti HLS lobby.