At our airfield we all normally give a radio call on Downwind and then on Final.
So imagine my quandary when descending through 750ft on base leg, when someone announced that they were on base leg.... Was he above or below me? I just could not see him. So fearing he was either 20ft above or below me, I announced that I was also on base and at 700ft and I would continue at that level for a go-around.
After I turned onto RW heading, I saw him about 300ft below turning onto Final.... Where he came from, nobody knows...