Some farmers face ruin if restrictions are not lifted
Even the Environment Secretary Hilary Benn has admitted he is puzzled by aspects of the latest foot-and-mouth infection.
Here, our environment correspondent Sarah Mukherjee responds to the most important questions being asked so far about the outbreak.
Is this the same strain of the disease as occurred in the previous outbreak?
Defra (the Department for the Environment and Rural Affairs) have now confirmed that preliminary tests suggest the strain of the disease found in Egham yesterday was the same as the one that caused the outbreak elsewhere in Surrey earlier in the year.
In some ways, this would be good news for the industry, as it would give scientists much more to work on when it comes to tracing this outbreak back to the original source.
How did it get into the farm?
The incubation period for the disease is relatively short in normal conditions - between two and 14 days - and it's also a virus that breaks down quickly in UV light, so sunny weather tends to halt its spread.
However, in the right conditions - dark, cool and neither acid nor alkali - it can survive for longer. So, one theory is that it found itself a pocket of the right conditions somewhere in the environment.
Mystery surrounds how the virus managed to survive for so long
But the smart money, as one vet put it to me, is on it having got into the sheep population, outside the rigorously tested surveillance zone. Sheep, unlike cattle, can get the disease without showing many symptoms, and even experienced vets have problems in diagnosing it sometimes.
What does this mean for farmers?
Total shutdown for livestock farmers. Many have been stranded at shows and sales around the country, and will need special movement licenses just to get back to their farms.
Farmers' leaders are devastated, as this has come at the busiest time of the year. Some hill farmers rely on this sale season for their entire annual income, and face ruin if they have to feed animals over winter that they expected to sell.
Will restrictions be lifted earlier in places where there is no disease?
During the outbreak earlier in the year, there was a big push to lift movement restrictions regionally, as the outbreak was relatively confined geographically. Although it's very early days, it's likely the farming community will be asking the government to consider this if there are no more cases in the next few days.
Despite precautions, the infection has returned
Certainly, the devolved authorities in Wales and Scotland, may argue that there are farmers in France who are closer to the Surrey outbreak than some of the hill farmers in remote areas of their respective countries.
Given the devastating economic effect a movement ban will have on them, Scottish government vets say they will be assessing the case for lifting movement restrictions - but only after the origins and movement of this outbreak are fully clear.
There are many sheep in transit at the moment from the Scottish islands which have been given special licences to come to market. There have even been some movements to farms, from these markets, but only after the animals have been extensively checked.
The situation is so bad on some Scottish islands, emergency slaughter regulations may well be put into place in order to avoid welfare problems.
What happens next?
The most important thing is to find out how the virus got to the farm - and there are intensive investigations going on in the area.
The cabinet's emergency response committee, Cobra, has been meeting to discuss what to do next. However, some farmers within the surveillance zone have complained that they have been given scant information about the location of the new outbreak, and what areas they need to avoid.
What about vaccination?
The other issue is: will the government consider vaccination this time?
Some sources said government vets were close to considering this during the earlier outbreak, but it would have significant implications for our export status - British meat exports are worth more than a million pounds a day in normal conditions.
However, campaigners at the organic movement, the Soil Association, have long argued that vaccination should be used as a first line of defence in a foot-and-mouth outbreak.