This is the opinion of the National Organiser of the Spider recording Scheme, and whilst everyone can make mistakes, in this instance I would lay a lot of money on this opinion. If you can obtain a decent closer image of this spider, in focus, then this identification can be doubly and trebly confirmed.
Discussing false widow spiders, which are becoming the bane of arachnologists' lives because of the rubbish spread by the irresponsible Press, there are a number of Steatoda species found in Britain, all so-called 'false widow' spiders. Three are possible in or near buildings, Steatoda bipunctata (very widespread), S. grossa (widespread and sometimes very frequent in the southwest, but becomes much scarcer further north and east, but in the last few years seems to be increasing) and S. nobilis, the one which gets the press for biting humans (originally confined to the south coast, now increasingly turning up elsewhere in southern England). Steatoda nobilis has on occasions been responsible for bites, and Steatoda grossa is also known to be able to pierce human skin, even though many of the cases publicised for this are almost certainly due to another cause, and there are other spiders capable of piercing human skin.
Steatoda nobilis is widespread and numerous along much of the south coast, has been established in the Southend area of Essex since at least 1990, and in more recent years had spread widely and come much more numerous in England as far north as Norfolk and also south Wales (see summary). Although the media make a big fuss about supposed bites from the spider, most are almost certainly unrelated to any spider. Most 'spider bites' have other causes and the media do not present an accurate or sensible story. Generally speaking people are vastly more likely to be stung by honey bees or social wasps, and spider bites are very rare. Steatoda spiders catch their prey using an untidy 'scaffold' web in corners, under window ledges etc and are generally unlikely to leave the webs to wander around, except when the males become adult and are looking for females. One should avoid handling the spiders, but trying to exterminate the spider is unlikely to succeed for any length of time, since others will move in from the general area.