Masonry paints are the first line of defence for our homes against the weather, but we have interpreted this as meaning that we must make them as water-proof as possible. This is a big mistake on older solid walled properties. On houses with 'breathable' walls we should in fact use breathable paint as these allow any moisture in the wall to escape, otherwise we lock in the moisture and thus make our walls less efficient thermally and also increase the risk of damp and mould.
All breathable paints need to be directly applied to the stone / brick / lime render, so bear this in mind when choosing your paint. Eco Home Centre recommends either: Silicate Paint (very long lasting but quite expensive) or Limewash / Lime Paint (cheap, superb colour and ideal for lime putty renders).