Mal Rowe posted a photo of a trammie climbing on the roof of 948:

http://tdu.to/m/191911/safe-work-practices-1960s-style http://tdu.to/m/191911/safe-work-practices-1960s-style

There's a famous picture of Robert Risson on the roof of a tram showing his troops how to do it.

I suspect it has something to do with the union's concern over members having to climb on a tram's roof to tie a rope to an errant pole.

Pans sure took a long time a-coming, but IIRC they were trialled on at least one tram after this.

david mcl