ATC would need to be asked why there was no objection at the time, but one reason why perhaps they did not say anything at the time was because they knew the weather to be poor and the pilot to be working hard and simply chose not to highlight the point until a later stage. Why put undue pressure on a pilot in poor weather, who has just effectively asked for a weather div and who is manoeuvring at low level to position for finals?
Furthermore, rules are there for a reason. Sometimes rules need to be broken, I agree entirely. But that is in emergencies, not because "we need to get the job done." If the rules don't allow you to get the job done, then you need to question the rules or question what it is that you are trying to achieve. That's not Cook Book Piloting, it's simply being professional. Maybe you didn't intend for it to come across the way I have read it, but "no harm, no foul" is pretty cavalier, wouldn't you say?
I know of professional pilots who have done what this pilot appears to have done, i.e. push the weather limits inside London CTR. I don't like to admit it, but I have been one of them. In fact, the circumstantial evidence is that G-CRST was probably being flown like that. "No harm, no foul" flying, getting the job done. All very professional, non-Cook Book Piloting.
Right up to the point that the aircraft flew into an obstacle and killed someone who was just going about his business, walking to work.
YOP:
Of course the elephant in the room question is did pride stop him declaring an emergency and being recovered by clearance from Heathrow?
Or admitting at Lambeth Bridge that today is not your day, climb back up in the gap in which you're descending until VMC on top again and head south, RTB Redhill.