Correct pointing mixture..

Evening all...I live in an old sandstone cottage which when I moved in had been reprinted using a cement / sharp sand mortar mix and a few damp problems...all raked out back to original lime mortar and repointed using NHL/ sharp sand mix and damp problems disappeared. The place had an extension added using thermalites tied to a random sandstone block outer...apparently this was laid/ pointed with cement, lime, 4 soft sand mix.....and visually leaves a bit to be desired......I’d like to re point...so the question is, what’s the best mix. Obviously unable to completely remove all the cement based mortar and replace with lime mix so left with either raking out and repointing with lime mix ..or a cement, lime 3 sharp 1 soft sand mix....views anyone?

There's no correct one mixture on cavity walls as such, other than never put cement into the mix on a solid wall. You can build a cavity wall and use lime mortar if you wish, thus keeping the same colour in your circumstances. Lime mortar gives, thus reducing cracks.

Rule of thumb is, the mortar must be weaker than the substrate, ie. weaker than the brick, brick, stone etc..

Never put feb tone in lime mortar.

Google Rob Songer, he's on youtube and has some incredibly complex work that he's done and also some hugely helpful videos on mixes.