HP, hi, I was the GMC controller who you enquired about the reason for the go-around to.
Its all been explained really, Cat B police helicopter racing towards Slough which meant 3 go-arounds and a few broken off by radar.
I wasnt in the tower at the time of the airshow but I would always expect the initial instruction to be the standard "Go around, I say again go-around acknowledge" after which any non-standard turns/altitudes would be passed. Were you the third to be sent around? As far as I am aware the first followed the standard missed approach, second straight ahead and the third went to the right.
We have a lot of trainees in the tower at the moment which may have led to the lack of information being passed straight away. Multiple go-arounds are challenging even for a valid controller, never mind a trainee.
Glad we helped make your day a little more interesting!
At least the stand guidance was on when you got to T5
Cheers!