I got my Covid-19 test result in an email this morning. It was negative. Did the swab test Thu morning before 8am (as they ask you to do that on day on collection), then put in fridge. Collected about 5pm on Thu, and result this morning. So what's that about 3.5 days (84 hours ish) from collection?
Remember this is the randomised NHS / Imperial College Covid-19 testing to inform Government action, so it may be on a fast track than other testing (if you have symptoms etc).
Edited to note you were also doing testing for the randomised Covid-19 testing from those on NHS GP registers.