The announcement today by Boris Johnson that we are gearing up Covid-19 testing from 5,000 a day, to 10,0000, to 25,000 to 250,000, and the endorsement from the government's Chief Scientific Adviser Sir Patrick Vallance that this could theoretically happen in weeks, was the most important Covid-19 announcement on Thursday.
Many in the NHS and in the wider scientific community see this as a shift in policy that should have come earlier.
But few doubt its importance in saving lives by making social distancing more effective because more accurately targeted.
And it creates possibility of an earlier return to something for all of us that would feel a bit more like normal life.
PS equally important is even stronger optimism on Thursday than on Wednesday from the Chief Scientist that a workable serological test is in reach, and which would give strong evidence of who has had the illness, even without symptoms, and who therefore has the antibodies that should deliver immunity.
On my show last night Sir Mark Walport, the UK Research and Innovation Chief Executive said mass serological testing could happen in months.
And again this gives hope that the severe restrictions on our freedoms we are experiencing would have an end.
PPS. History will be the judge, but those intimately involved in government in the battle against Covid-19 insist the move to mass testing is not a policy shift.
A source said: "It's what we've been aiming for since we realised this [problem] wasn't going to be contained... mass testing is critical."
Coronavirus: Everything you need to know