I am assuming there was no AT? If you hear another aircraft joining in my view it is well worth saying explicitly where you are and what you are doing in the circuit because it at least means there should be two pairs of eyes looking for each of you rather than just you looking for him.
we have a radio service who is able to advise (callsign 'radio'). I'll definately try out your advice next time I'm in the air. makes a lot of sense. I always call downwind as soon as practical after turning from crosswind, chatter permitting.