Which is 1.5 weeks ahead of the dosage schedule that the JCVI set.
I can only assume that the Pfizer doses we have in stock are all reserved for second doses, with no new supply coming in, so we might as well inject people with them now, a bit closer to the date that Pfizer says we ought to have done.
Indeed, 64% of people who had a first Pfizer dose have also had a second Pfizer dose, compared to 26% of people who have had an AZ first dose (data further down that page).
I don't have historical records of what doses were given out on previous dates, so I can't see if that's ahead of the curve for both, or just Pfizer, but I'm betting it's just Pfizer.
*Well, kinda. Obviously the Pfizer doses are intended to be given after 2 weeks. But this is them being ahead of the schedule they set of 12 weeks between first and second doses.
Original post on Dreamwidth - there are comments there.