I'm not aware of Newark closing...
Theres 4 factories left. Wissington, Cantley, Bury and Newark. We have explored a fair few closed ones over the years tho. Ipswich was my local one and a great explore. In addition there was it this one, York and Kiddeminster all there at the same time for a year or two. The one we all missed was Allscott in Shropshire. In 2007 you had your pick of all 5 plus a bit of Nottingham that was still left behind derp.. Then think how many cement works and all those other simlar places there were out there.. that's why people didnt explore them so well. These kind of industrial sites were ten a penny. You didnt have to seek out every last bit of them all to see some really good stuff so not many people bothered.