If anyone is looking for a way to get hold of stock Sony Xperia wallpapers for your Xperia I highly recommend the Android app called "Stockie".

It contains stock wallpapers from all phone manufacturers which they ship on their phones and you can easily downloaded them or set them as your wallpaper.

The app also has separate lists for each manufacturer so just find the Sony list and you'll find alot of wallpapers there going back to 2014 and earlier.

I used the app to get the latest wallpaper for the Xperia 10v and it looks great.