Thanks.
1/60 was enough...because of the UWA's sensitivity to angle and movement, even slow tracking with one at the wider settings will give you lots of movement. ; I think you could generate some panning blur at 1/100 with a UWA, even with something as slow as the train.
Overcast definitely helped, and I was at F8 too so I was stopped down a bit...could have stopped down more if needed, but F8 was enough with that lens.