I wouldn't recommend using standard Emulsion like "Weathershield". That's probably why the coating from the previous owners is peeling badly. I have a similar situation here, recoated with the aforementioned and it peeled again after a year!
The wall needs to breathe more as you reach the external face to allow moisture to evaporate rather than be trapped causing the peeling or in a worse case (as mine over the last cold snap) cause the the render to fall away with freeze thaw.
There are plenty of natural breathable paints like St. Astier and Beeck. To lime wash you would have to completely remove the previous coat.
A coat of bonding sealant would make the paint last longer but could have disastrous affects on your wall, possibly leading to moisture being trapped internally leading to damp and mould etc.
I'm looking into other possible remedies myself as it happens so we'll see if there are any more suggestions here.