I was just brushing my little kitty (5 ish months old) and I found one single incapacitated flea. It was lying on it's side with its legs moving.
I actually treated them today with frontline (do it every month - I know it's not the best but vet said it's sufficient as prophylaxis) so maybe that's why the flea is worse for wear?
No other signs of infestation whatsoever. Not noticed any itching or scratching from either cat, not been bitten at all but I've never even seen a flea (I only know it's a flea from google!) And I've no idea what other symptoms I should look for, or what else I should be doing if it's unlikely that we have just one blighter!