I do sympathise as they truly terrify me. I saw that in the DM yesterday and couldn't look at it because of the pictures. Firstly they come inside to mate somewhere warm, that could be what you saw. As a lifelong phobe I'd say conkers don't work, keep your doors and windows closed as much as possible. I put ant powder in the recesses of external doors and that seems to help. Don't believe it if a poster comes on here, as they do every year, and tells you the big ones are in your house all year but you don't see them. They are coming in from outside.