Painting over filler

[rubberduck]

Hi

I have a rather larger area of filler (polycell white - good stuff) that I need to repaint. Do I need to prime the area first or is a watered down emulssion good enough? The area need to be painted with a magnolia (ish) vinyl matt emulsion. What should I do?

Thanks

 

[Maccapacca]

A watered down coat would be good. There's no bed to prime it.