Very happy today! I got a couple of emails from Mike Watson who played on some of the original recordings.
He confirmed there was no sheet music for the Abba sessions except for the string section.
He did tell me something I haven't heard before - that he played the bass on 'Gimme, gimme, gimme, a man after midnight!'
This track had always made me wonder as it didn't sound like Rutger but also not particularly like Mike. Mike even dropped in some popped notes on this one.
Mike also confirmed that he recorded the tracks with his 1966 Jazz bass with Schecter pickups. Better get updating my article.
Oh, also Mike confirmed that Rutger played the bass on Fernando contrary to what I wrote.