I wonder how observant the keeper was? Employee who just paid to feed, didn't notice a few not interested ?
In the meantime, has it been carried OUT of the units?
Academic... it got IN so it's OUT THERE... More likely it'll be the dead birds being badly disposed of that also spreads it. There's stories locally during the F&M outbreak of lorries driving through town with blood spilling out of them on each corner. Even with typical exaggeration there'll be some truth. the intial spread was more to do with the road network than winds and animal migration.
I'm guessing all Gov wants is to slow the thing down so there isn't an absolute shortage of birds/eggs at any one time. It'll clear when it's been through the wild population and they have died/become immune.
Got in or was brought in? (as per 2007)
I think you will find that the farm had the turkeys in at least 5 sheds so one has to ask how the virus got into most or all of the sheds (which must have happened for “most” of the birds to die before the cull started).
Re-reading the info on the 2007 Bernard Matthews outbreak is rather depressing:-
https://en.wikipedia.org/wiki/2007_Bernard_Matthews_H5N1_outbreakEspecially the :-
“The cause of the outbreak was not determined “
The entirely predictable political stances e.g. :-
“The Hungary link was dismissed by the European Commission on 12 February “
and
“On 11 February the investigation revealed that turkey products were still being transported, in both directions, between the plant and Hungary with EU regulations being cited as the reason why a transport ban could not be imposed ”
And the rapid re-establishment of business as usual:-
“Bernard Matthews was given permission to resume its shipments of poultry between the UK and Hungary from 17 February even though Defra indicated that Hungarian turkey products remained the "most plausible" cause of the outbreak. “
that was just 14 days after the initial confirmation of H5N1 as the cause.