Well, if you're in the SE or S of England, these spiders are not a rare, or uncommon sight.
They are the much maligned noble false widow (Steatoda nobilis). Despite their billing as the UK's most venomous spider, they are not dangerous, certainly not deadly. Your examples are outside, therefore pose an almost insignificant threat to your wellbeing. Bites tend to be the result of a spider being trapped against the skin & crushed.
They are typically docile, females tend to make a web & then stay close to home, your examples don't appear to be fully mature, by the stripes around their legs.
They are well established where I live & can be found in (if they are out of the way, I leave them be) & around my home, office...even seen them living on traffic lights/pedestrian crossings in town. They typically go unnoticed. Whilst they like man-made structures & may live close by to us, they are skittish and tend to bolt for cover if they can, when disturbed.