And now for the river trip...
That's the
London Eye, sometimes known as the Millennium Wheel, in the background.
It's widely believed to be powered by the inexhaustible supply of hot air from the nearby Houses of Parliament.
The walk from Westminster pier to Trafalgar Square took Sundae and parents past the Household Cavalry mounted guards in Whitehall.
Note the partially visible words of caution on the right-hand side of the second photo above.
I hope that there will be some more photos before the day is done and I'll post them ASAP.