A false widow (Steatoda nobilis).
False widow spiders aren't life-threatening, the Guardian reported, but their bites can cause headaches, nausea and lethargy in about one-third of instances. They've been spotted inside homes across the country each autumn since first arriving in England in the 1870s, per the BBC.
» Why you shouldn't kill that spider in your home
The risk also proved too much for Ellen Wilkinson Primary School, Star Primary School and Rokeby School, all of which joined Lister in closing Wednesday, the BBC reported.
London's Newham Council warned all schools and nurseries nearby to "check their premises carefully for these spiders," the network reported.
Rokeby headteacher Charlotte Robison told parents in a letter it also made the "difficult decision" to close until Oct. 29, noting "it is in your child's best interest to remain at home and not at school," according to Sky News.
Star Lane headteacher Lisle Von Buchenroder told parents staff believes the "infestation is outside the building" and needs to "be treated immediately before the eggs start hatching."
» Here's how to identify (and get rid of) venomous spiders in your home