Sandstone lintel repair

[Matt955]

Hi guys just after some advice on my sandstone three piece lintel. I have had water ingress and one side has slipped, I have removed and cleaned the stone and it has cutouts for securing it in place but what is the best product to use lime mortar? There are holes in the top of the stone to poor in to the groves.if that makes sense.
Please see pics
Many Thanks

 

[^woody^]

I would suspect that the original mortar is lime based so would not be an issue to use that.

As for the water ingress, would that have been from the parapet?. If so, it would need dealing with.

 

[bobasd]

OP,
your water problem, as above, is most likely the short flat roof and its draining arrangements.

there's also a metal gutter down pipe coming through the masonry with a connection inside the masonry. but no sign of water damage.

if you post pics of the flat roof - at the edge, and where it meets the slate pitched roof then maybe something else could be suggested?

fwiw: your pic shows a sand & cement fillet instead of lead flashing at the pitched roof abutment.