This is a missing sector orb weaver (most likely Zygiella x-notata), a harmless spider often found inside & out of our homes. I should think most people have some on their window frames, you often get several around the same pane.
Thanks so much for the reply.
I dont want to jump on the "false widow bandwagon" but i have a 12 month old baby girl i need to consider.
Is it normal for this species the have the triangular markings on their abdomen simelar to that which we are led to be FWS?
I have also been told that FWS have shiny jet black bodies? Is this correct.
Would false widow spiders exist in such close proximity to one and other?
I have at least 5-10 of these spiders on eack window pane.
Sorry for all the questions, but i am curious more than anything else.
Have to say, they are intersesting creatures.
Zygiella's markings might be seen as more of a "feather", "flare" or "chevrons". They have stripey legs even when mature. Their heads are typically brown, with a thick, dark, central stripe and a fine dark line around each side. Their webs are the typical orb web that hangs vertically and in the evenings the spiders hang vertically in the web.
Steatoda nobilis' markings are more usually described as a "skull", "shield", or even a pentangle...perhaps like a monopoly house? As they grow, females can lose the lower part of the marking and it look more like a "USB" icon...here's a female S nobilis...
...this is a young one, notice there is some striping around the legs still, the head is a more uniform colour, you can't see so easily from this photo, but she is hanging horizontally under her web, belly up.
Here she is again a few months on...legs are more of a solid colour now, still hanging belly up. Markings are stretched & faded....
She is still in the same place & hasn't moved more than 6" in any direction. Her web is messy and more like a hammock/shelf. She bolts for cover whenever she feels threatened.
Both Zygiella and S nobilis are very variable in colour. Zygiella often live in very close proximity of each other. S nobilis less so, there is a spiderling about a yard away, I haven't seen any other females indoors. Males come & go, she doesn't seem to mind the much smaller Zygiellas living close by...occasionally chases them off. I would be surprised to see 4 or 5 S. nobilis on the same window pane.
There are other false widow species in the UK, but S nobilis is the one that grabs the headlines & the one most likely to be confused for a Zygiella species.