Ashwin, having decided my problem has to be something very basic I have been thinking right back to roots and have come up with a theory which might be the cause.
When I switched from PC to MAC I needed to set up an iCloud account. The only email address I had at that time was a non-iCloud ISP so I used that as my identity. Then I was able to set up a couple of iCloud email accounts.
Now, during Android setup I go into my account (old ISP email address) to generate the App Specific Password. Then when I try to set up Android for my iCloud address it tells me the Identity or Password don’t match - it now occurs to me that is probably because the App Specific Password is referencing the OLD email being the iCloud identity, not my iCloud address.
Intent on rectifying this I went back to my iCloud account to use the “change identity” facility to install my iCloud email address as my iCloud identity. Nope! iCloud will not accept it saying I “can only add @iCloud address already on file in your account”. Very strange because my iCloud addresses work perfectly, so does that mean that my iCloud email addresses are NOT part of this iCloud account?
If I cannot change the identity of the iCloud account should I just scrap that account, disable or ignore it somehow, then set up a completely fresh iCloud account. My concern is that by doing that I might lose all my mailbox facilities and have to start again from the start point. I use time Machine to backup everything so could presumably reload somehow.
Assuming my basic theory about the App Specific Password is feasible, do you have any ideas how I should proceed?