I've got an unusual job just across the road for a mate of mine. (And then I'll be going back to trying to sell some paint stirrers for a while etc). It is, wait for it - part lime mortared brick, part bathstone, and part very rare styrene acrylic copolymer masonry paint. A kind of breathable rubber number
. Anyhow Keim have suggested Soldalit and their primer - highly breathable, all good aside from the price, about £350 just for the front of a normal terrace house (two colours and...
Breathable Masonry

Breathable Masonry