
Scientific name for this spider is Steatoda and is the largest of 3 similar false widow spiders (Rabbit Hutch Spider and Cupboard Spider being the other 2) it measures up to 14mm and although not native to the UK, but were thought to have arrived in banana boxes in the late 1800s.
The false widow spider is often heard about in news stories about bites and the effects it has on its victims. However; despite this there are very few confirmed widow bites and thus extremely rare for them to bite. The few recorded incidents are of the spider being roughly handled or from accidental contact where the widow bites defensively.
Symptoms of a false widow bite can include pain, swelling, nausea, tremors, altered blood pressure, impaired mobility and in rare cases minor wounds and severe bacterial infection. As of now there is only 24 reported and confirmed cases of bites.
Formula C+ will kill them, but I wouldn’t get to close to avoid annoying them.