That is a lovely green dress.
We get carriages going past reasonably often, although mostly when you see the police bikes it's just for a car or two.
I don't know if the carriages had anyone in them today, as the little windows were completely shuttered-up. That wall is the side wall, if you like, of BP - servants quarters or offices, I think - so they were on their way to the palace entrance, which is sort of just around the corner.