Andrew Eldritch is reported to have said that the only time she picked up a guitar was to film the videos.
(Which was not quite true, however.)
In the 1959 video she appears to be playing the piano, but it's hard to tell whether she really did.
The relevant discussions on Patricia Morrison and her whereabouts can be followed
on Heartland under http://www.myheartland.co.uk/viewtopic.php?t=861
or here as to her (as well as other peoples') contributions to Floodland
After leaving The Sisters, Patricia Morrison became a long-term member of The Damned.