After the Supreme Court judgement declaring the prorogation illegal, Boris Johnson flew home to attend to parliamentary business. Why did he do this? Was it for personal gain or is he required to by parliamentary rule/convention? Was he summoned back by some official process?
It seems to his personal detriment to attend, as the sanctions which could be imposed on him by the house (no confidence, leadership election) all waste that same time that the attempted prorogation seemed to be designed to waste.
He seems to be taking a strategy where he gently implies illegitimacy of the post-prorogue parliament, the Supreme Court decision, "will of the people", etc, which he could have effectively achieved by just by carrying on his foreign business and leaving parliamentary business to his deputies. Prime Ministers are away for a couple of weeks from time-to-time.
Was anything in statute or long-held convention compelling him to return? If not, how was it to his political advantage?