Doing a factory reset is generally not recommended. Have you wired the PLAY:1 to your router with an Ethernet cable? You’re adding it as a separate room, not a surround speaker, correct? 

Thanks for the response. 

I had connection with the new app, a change of router lost it. I contacted support who said that I would have to wait until the end of June before new code would include “old equipment”. I was without sound for 3 weeks.  Support got me to use the ethernet cable, but that didn’t work and they recommended a factory reset.  Once the new app was functional, I could originally add Playbar but not Sub, and I could not link two Play 1,s as surrounds, although I could get them to work independently as a stereo pair.  10 days later, I could add sub and stereo pair.

The two Play 1’s in the outdoor area showed the same pattern.  I did a factory reset on one and it then appeared.  I tried the same on its partner in the pair, but doing the factory reset left it flashing orange and white, and did not go green.  The app still does not recognise it.  

So yes this pair is now in a separate zone

It sounds like there might be a hardware fault - you can either speak to Sonos Support again to see if they can assist you to get it setup (recommended), or perhaps see if you can get it to flash green from a reset - but I would definitely cable it to the router if you do try the latter option. My thoughts are start with Sonos Support, see what they say and then go from there.