Smooth Bagging Options?

Hello Everyone

We've just had some double brick walls built which we want to bag and paint. It has been suggested to me that for the inside of the house a mix of plasterers sand(?) and cement will give a smoother finish.

The old part of the house has some walls that seem to be "bagged" in the past with white plaster. This part looks really great.

What we are after is being able to see the brickwork, but have a surface to paint that will be relatively smooth to touch - i.e. avoiding the sandpaper effect you sometimes get with bagging.

I'm interested to know any ways of achieving this, it doesn't have to be bagging then painting if an alternative exists.

thanks a million........

p.s. not sure if this is a Brickwork or Render post!