Which mortar mix for repointing below DPC in 1930s house

[VDubDan]

I've got a 1930's, solid wall, build. I've had to excavate a section for some drainage work and the pointing is pretty poor - well, in fact, you can barely see any mortar in parts so I'd like to joint it up before backfilling.

Just wondering if normal sand/cement mortar will be okay - can't see that it needs lime here, but wanted to check?

 

[Mrs Ten Names]

I assume you are referring to repointing up to the DPC, if there is one.

Usual 1:4 cement mortar will be OK. with a soft sand. You could add a little lime or additive to improve workability.
If you really think it's lime mortar, and you want to use lime mortar again, you could use 1:3 lime mortar with a NHL 3.5 lime rating, and sharp sand.
But the use of sharp sand makes it more difficult to work with.

if it's really wet around there, you could use a 1:3 mix with a NHL lime rating of 5, and a sharp sand.