By David Shukman
Environment correspondent, BBC News
I could hear it in the voices of Whitehall, even before the outbreak was confirmed - the heavy hearts of people who really thought they had fought foot-and-mouth over the summer and won, only to see it return with a vengeance.
"Here we go again," said one official grimly.
Last Friday officials thought foot-and-mouth had been beaten
A familiar pattern will now be repeated - the white-clad veterinary officials descending on the farms, the plastic tape on gates and paths, the cycle of news conferences, the desperate hopes of the farmers' leaders rising and falling with each new development.
Only last Friday I was at the ministry handling things, Defra, attending a news conference that was meant to put a full stop to the August outbreak.
The investigators released their findings about the likely cause - a series of bio-security breaches at the government-run Institute for Animal Health.
And the government's chief veterinary officer, Debby Reynolds, gave her summary of the summer campaign, ending with the triumphant declaration that the disease was now eradicated.
The talk that day was of exports of British meat resuming, of the final restrictions being lifted and of Britain being on course to win back its coveted status as "free of foot-and-mouth".
In a matter of days the whole atmosphere surrounding this threat has soured
I remember wondering at the time how they could all be so certain, and sadly their confidence was ill-founded.
In a matter of days, the whole atmosphere surrounding this threat has soured.
Last week, the tone was one of relief that, unlike in the 2001 epidemic, the authorities had responded speedily and comprehensively enough to conquer the virus.
Now, it seems all that was too optimistic.
One of the reports into the August outbreak was by Professor Brian Spratt of Imperial College. I have just looked at his work again. It contains some very depressing details, which did not seem relevant last Friday.
The virus can survive in soil for up to 28 days, in water for up to 50 days, and in hay and straw for up to 20 weeks. So maybe it survived the first outbreak and started this new one.
Or it's a totally new strain - and that would even more alarming.