Painting Skirting but it's Currently Varnished

[ms1983]

Existing skirting is varnished over the natural wood colour.

I want to repaint this white.

From reading it seems the best way is to:

sand
prime
paint (gloss or satin)

Do I need to clear varnish over that again?

Is there anyway I can just paint straight onto the existing varnished wood without having to sand and prime? i.e. any "special" paint. I know I'm looking for a short cut but I've a lot of skirting to get done.

Thanks