Pay as You Go on Note 4

[yottie]

I already have an O2 pay as you go sim on my Sony Experia J, very rarely used except emergencies

Have also a Samsung Note 4, used for drone etc. This does not have a sim card but it seems a good idea to have one for (very) occasional use. It would also seem a good idea to install another O2 sim on the Note 4, I take it I would get a different number on the new sim.

 

[IT Minion]

Don't forget to keep using the PAYG phone every now and again, otherwise the SIM can be deactivated.

They would have to be separate numbers. You could, in theory, use something like Skype to have a number shared on the devices but that doesn't seem practical/helpful for your situation.