MK4 vehicles use UIC connections for TDM and FDM so the RCH cable aren’t required for normal use. RCH cables can be used for TDM (as it is on 86/87/90s and MK3 DVTs) but not on MK4s. Removing RCH cables reduces interference potential on the TDM system (water ingress etc) it also has the benefit of tidying up the front of the loco.
The No 1 end flaps were sealed up prior to HGR - Heavy general repair (not mallard refurbishment - that was a rolling stock refurbishment on MK4s). It appeared at the time of HGR (when 91s became 91/1s) that the job of sealing the flaps appeared to have been strengthened, before HGR in was not uncommon to see the area damaged easily by bird strikes etc.
