Thanks No.9, I did have a resident
Zygiella x-notata at the top of the window outside so that is a possibility, if anyone knows what their babies look like
If you look at this pic of the other one I had not far from the end of the window, the underside of the abdomen is yellow with a black stripe, and the thorax is yellow with a narrow black stripe along the side, both of which the spiderling has.
