Can you confirm that you are following the steps in this article: What can I say to Alexa in the BBC Sounds skill? | BBC Sounds

I suspect that an instruction to play in a particular room is going to confuse it.  In my set up I use Alexa Groups such that a group contains an Echo Dot as the Alexa device and the corresponding (non-Alexa) Sonos speaker as the speaker.  So if I am in the Living Room I can just say ‘Alexa, play BBC Radio 4’, for example, and it plays on the Living Room Sonos.

There may be a way to specify another Sonos room as the target when giving the command, but i don’t know what it is if using BBC Sounds.  I’d be happy if anyone could enlighten me. 

I suspect this behaviour arises because you are using the Alexa-BBC Sounds integration to launch the station, rather than the Alexa-Sonos integration.  And BBC Sounds knows nothing about multiroom.

And I don’t imagine that BBC Sounds can be chosen as the default radio player in Alexa?

Edit - it may be worth my pointing out that this is how I have been been playing live BBC radio for ages.  This has not changed with the addition of BBC Sounds to the Sonos app.

Apologies for my latish reply..New Year got in the way!

I think I’ll resign myself to Alexa and Sonos not working together as expected(?)

I can still play live BBC radio on my Sonos using the Sonos app on my phone which is an improvement on a year or so ago when it didn’t work at all

Thanks both

It is how I would expect it to work (or not work), given how things fit together.  I am happy with how it works for me.  I can use Alexa to play BBC radio on the default Sonos speaker in every room.  I just can’t be in the Bedroom and launch the play in the Dining Room (for example).  But I never want to.  Of course, everyone uses their system differently.