it's fairly easy to make a really good antenna
Yes, I know, I've never quite got round to bothering. Main reason is that the conduit from the attic to the living room is a piece of half inch central heating pipe embedded in the concrete wall - it's already got a TV aerial downlead, a VHF radio downlead and a set of speaker cables in it, there's no room for another co-ax. (Although as we don't watch TV I suppose I could remove the TV co-ax to make room for it.)
Plus, I don't actually have the ethernet co-ax any more - someone who was obviously converting to CAT5 somewhat later than me took the whole lot off my hands!