Winter Olympics programme interrupted

It wasn't to allow for an aspect ratio switch perhaps? I've noticed some of the Olympic material has been 4:3 and some 16:9. Unlikely I know.

And even more unlikely - so that it was a seperate programme which started after the watershed?

Nothing to do with the watershed. In fact the majority of 'breaks' have taken place during the afternoon transmissions, mostly 12.30pm - 2pm and 2pm - 4pm.

And on every occasion, the programme break has facilitated a change in focus to a particular event. However, 12.30pm - 2.00pm Snowboarding, followed by 2.00pm - 4.00pm Curling.

Why interrrupt coverage just for Marketing to annoy us? It serves no purpose whatsoever.

No - all of the BBC Sport stuff has been broadcast 16:9. The curling was pillarboxed 4:3 within a 16:9 frame (as usual with BBC Sport) rather than being broadcast as a 4:3 signal (via the various platform routes)