Allium

Another grey, and intermittently rainy, day. It also feels cold, certainly for July. Plans for visiting friends for a garden meet-up have been cancelled.
We planted this allium in the autumn of 2018 and last year it failed to produce a flower. This year, it has been very slow progress to get to the point where the flower seems about to open. It stands now at almost 3 metres tall and I find the shell that covered the flower and has slowly opened as attractive as the emerging flower head and certainly more fascinating. How many more days (or weeks) before it fully opens?