Spoke to my daughter tonight and she has been invaded by the above in her 4 bed house which is only 1 year old.
She dosent have any windows open and the L/Birds are 2 different colours. some are black with red spots and the others are red/orange with black spots. She is a bit worried as she has a 9 month old baby.
They may be Harlequin Ladybirds which are destroying our native ones. If you Google there are quite a few articles.They are very hard to get rid of but there is quite a lot of advice on the net in what to do. I read the best thing to do is to hoover them up and throw away the bag..we had a few in the Autum but I think they are all gone now.You literally have to seal every gap with a caulk gun to stop them getting in.They seek shelter in the Winter,stain walls and furniture and smell of nail varnish apparently.