No service, only a mess (3)
I think a tie is out of place in a hot working environment. However nearly all Arriva buses are equipped with air-conditioners. Surely there is no point for the GWU to make a fuss about this.
I suggest these drivers are all issued with clip-on ties, and when they are not driving, having their break, are not in a bus, or in a non-air-conditioned office, they may take off the tie.