Daily change in reported cases by specimen date for England though
71702 cases in total today
14785 today's specimen date - LFD's and pillar 1 PCR's mostly I believe - ~26% same date, but not really indicative of community PCR testing
~56% specimen day before
~13% specimen 2 days before
~7% specimen 3 days before
~1.6% specmen 4 days before.
London is 20%,52%,20%,6%,1% so if anything a slight delay from 1 to 2 but less 3 to 4, but not indicative of hugely different performance for London (less 3/4 would suggest to me postal tests in more rural areas often take longer as you would imagine)
Boys possibly has the past data to say if this is much different to previous times of course.