Question for Anna really, but also anyone else who knows the answer:

What is the "ready mixed" lime mortar you can get from people like Tilcon or RMC
and how does it differ chemically from lime putty mortar? I guess it's a
mixture of sand and hydrated lime, but can it be used as lime mortar in the same
way as lime putty? If not, why not? I'm confused about this as all the
suppliers' literature I've seen seems to assume it is going to be mixed with
cement on site.

Thanks
Peter