Hope this is of help to others.
Certainly new to me, and following on from a helpful link provided in another thread, which gave a US supplier, replacement batteries for Sony3/650 now on Amazon UK - so more life for the classics, as it were !
They are the same as the US source, and come with special tools provided, and an excellent video which is very detailed, and easy to follow, and well within the average DIY fiddler-about .......
Considering the cost of factory refit, very reasonable prices, 350 - £16/650 - £22.
So put it on yer Bookmarks list just in case .........