Sorry to hear about you're ordeal but from what you have said most people who used the Tred were from the Splott area so if they were regulars I don,t think they would have walked that far up Clifton st. near the police station although it is not impossible for this to happen.
Also there was a club right behind the police station which the police used themselves and very few people knew about this.
Could it be possible they came from this private club.
Who knows . SW Police are well known for cover ups.