Yea this is one of the routes I sign. The ladder crossing at Tinsley Green enables a wide variety of movements to take place, and just looking at a Sectional Appendix doesn't give the whole story.
Red zone working is inherently risky, I take my hat off to the workers who have to do it in all weathers. I reckon every driver has experienced a moment when track workers on another line have suddenly realised that you are routed across to where they are standing - that's why you're sounding you horn with such vigour!
It looks like the COSS didn't appreciate that trains can be routed from almost any line to any platform at Gatwick. It's a shame that this incident has occurred, as the logical conclusion from this would be to close a line when this sort of work needs to be undertaken in future. Thus making this extremely busy route even more congested.