Neville didn't finish work on the farm until late. He went back to the field ,was it before or after Jeremy left ? He'd then have to take the two dogs out,which seemingly was a ritual every night,so by the time he returned,it would have been getting on for midnight.
He showered downstairs on his return,so it's anyone's guess what happened after that.
It had been originally thought that all were dead by midnight.? If that had been the time,what indications would there have been if this had been the case,or not ?