I obviously hope we never need to find out but what happens if in three weeks the situation in England is worse again? "July 19 will be a terminus date" as per today but if worse again do the concerns of Tory backbenchers trump all or do they react to the health data?

As well as hoping we don't find out I also think it's unlikely, but setting out roadmap with clear dates on 22/02/2021 and stressing "21 June" instead of "no earlier than" does make it much harder to delay twice even if it's needed.