Had an Emirates A380 thunder over here a few days ago at around 4000' - gotta have been a Heathrow go around; it was. Interestingly, it had been videoed for YouTube and buttoned up as "he was a bit fast on final". My money is on the preceding A319 which looked to be just clearing on to the high speed turn off as the decision needed to be made by the EK crew. Certainly the speeds reported by ADSB didn't seem excessive, around 135-140kt if I recall and the go around started at several hundred feet somewhere before the A30...