We recently came accross this spider in a box in Cornwall, the box was in a shed alongside items that had been inported from the USA. I've seen lots in the news about false widows but the images I have seen dontlook completely black on the back. Unfortunately I did not see its abdomen. What do you think?
This is a false widow (Steatoda grossa), not a black widow (Lactrodectus species).
They (S. grossa) are common here, but also established in the US. Often found in sheds, they seem less comfortable with living in close proximity with humans than Steatoda nobilis (who like windows/conservatories/porches,.but still like to stay out of our way & avoid direct contact if they can).