So long as you talk with the other aircraft in the area
No criticism of you +TSRA but your response is an indicator of the huge difference between your operating environment and that of the poster, who's from the UK. Over here it's still perfectly legal to fly IFR in solid IMC in uncontrolled airspace which may well be a military training area not publicised to civil pilots, and SPEAKING TO NO-ONE. Admittedly the only people doing that will be either civil GA or military, not CAT, but the history of CAT operations outside CAS in the UK is a long one. Most airlines with regular ops to/from airports outside CAS will have a requirement for a Deconfliction Service in their Ops Manual, but there are still quite a lot of places with daily scheduled pax services and no radar, so they get no info on traffic not speaking to their approach controller. Biggest threat to them is usually the military.