Full scale model of MI6 HQ built at Pinewood Studios backlot
Full scale model of MI6 HQ
What this model is used for, we don't know.
What we do know about the Westminster Filming and boat sequence:
PLOT: Bond and Swann in the boat are chasing and shooting at the chopper which will crash on Westminster bridge.
The crew have already built a full replica of the bridge at Pinewood studios, that's why we havent seen any actual chopper crash on location.